3,5-Bis (indolyl)-5-(indolyl)-2(5H)-furanones

ABSTRACT

Mono-, bis- and tris-indolyl-substituted furanones useful as color formers, particularly in carbonless duplicating and thermal marking systems, which are prepared respectively by: the interaction of an indole with mucochloric acid; the interaction of an indole with a 4-mono(indolyl)-substituted 4-oxo-2-butenoic acid; and by the interaction of an indole with a 2,4-bis(indolyl)-substituted 4-oxobutanoic acid or with a 3,5-bis(indolyl)-substituted furanone.

BACKGROUND OF THE INVENTION

a. Field of the Invention

This invention relates to mono-, bis- and tris-(1and/or 2substituted-3-indolyl)-substituted -2-furanones useful as colorprecursors, particularly in the art of carbonless duplicating as, forexample, in pressure-sensitive systems and in thermal marking systems;to substituted butanoic and butenoic acids useful as intermediates tothese furanones; and to processes for preparing said indolyl-substitutedfuranones, butanoic acids and butenoic acids.

B. Description of the Prior Art

Several classes of organic compounds of widely diverse structural typesare known to be useful as colorless precursors to dyestuffs. Saidprecursors have applications in the art of dyeing and coloring, forexample, in the dyeing and printing of textiles and in the art ofcarbonless duplicating. Among the more important classes useful in thecarbonless duplicating art, there may be named phenothiazines, forexample, benzoyl leuco methylene blue; phthalides, for example, crystalviolet lactone; fluorans, for example, 2'-anilino-6'-diethylaminofluoranand 2'-dibenzylamino-6'-diethylaminofluoran; and various other types ofcolorless precursors currently employed in commercially acceptedcarbonless copy systems. Typical of the many such systems taught in theprior art are those described in U.S. Pat. Nos. 2,712,507, 2,800,457 and3,041,289. However, to the present time, there appears to be no evidencethat the indolyl-substituted furanones constituting the subject matterof this invention have been employed as color formers, particularly incarbonless duplicating systems or in thermal marking systems.Representative of thermal marking systems disclosed in the prior art arethose described in U.S. Pat. Nos. 3,539,375 and 3,895,173.

Rees and Sabet in the Journal of the Chemical Society, 687-691 (1965)[Chemical Abstracts 62: 6475h (1965)] describe the preparation andphysical characteristics of 3,4-dichloro-5-(3-indolyl)-2(5H)-furanoneand 3,4-dichloro-5-(2-methyl-3- indolyl)-2(5H)-furanone without givingany indication of their utility. Barrett, Beer, Dodd and Robertson inthe Journal of the Chemical Society, 4810-4813 (1957) [ChemicalAbstracts 52: 100053e (1958)] describe the preparation and the physicalcharacteristics of5-(1-acetyl-5-substituted-3-indolyl)-2-(3H)-furanones. The compounds aredescribed as intermediates in a structural confirmation synthesis. Wehave now discovered that the compounds described by Rees and Sabet arereadily converted to colored substances on thermal exposure. Thisproperty makes them useful for incorporation into thermal markingsystems such as are used in recording and in duplicating systems.

Diels and Alder in Annalen Der Chemie 490: 277-294 (1931) [ChemicalAbstracts 26: 438 (1932)] describe the preparation and physicalcharacteristics of 2,4-bis(2-methyl-3-indolyl)-4-oxobutanoic acid and2,4-bis(1,2-dimethyl-3-indolyl)-4-oxobutanoic acid. There is noindication of the utility of the compounds given in the reference.Jackson and Naidoo in Journal Chemical Society, Perkins Transactions II;(5): 548-551 (1973) [Chemical Abstracts 78: 12439h (1973)] describe thepreparation and physical characteristics of4-(2-methyl-3-indolyl)-4-oxobutanoic acid as a chemical intermediate forthe preparation of the corresponding methyl ester for which no utilityis given.

SUMMARY OF THE INVENTION

In one of its composition of matter aspects, the invention relates tocertain 3-Z-4-Z₁ -5-Z₂ -5-(1-R-2-R₁ -5/6-Y-3-indolyl)-2(5H)-furanoneswhich are final products useful as colorless precursors in carbonlessduplicating systems.

In a second composition of matter aspect, the invention relates tocertain 3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2-(3H)-furanones which, inaddition to having the same utility as the final products, are useful asintermediates for the preparation of other final products of theinvention.

In a third composition of matter aspect, the invention relates tocertain 2,4-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-4-oxobutanoic acids which areuseful as intermediates for the preparation of the final products of theinvention.

In a fourth composition of matter aspect, the invention relates tocertain 4-(1-R-2-R₁ -5/6-Y-3-indolyl)-2,3-dichloro-4-oxo-2-butenoicacids which are useful as intermediates for the preparation of the finalproducts of the invention.

In one of its process aspects, the invention relates to a process forpreparing the 3-Z-4-Z₁ -5-Z₂ -5-(1-R-2-R₁-5/6-Y-3-indolyl)-2(5H)-furanones in which Z is 1-R-2-R₁-5/6-Y-3-indolyl and Z₂ is 1-R₂ -2-R₃ -5/6-Y₁ -3-indolyl which comprisesinteracting the appropriate 2,4-bis(1-R-2-R₁-5/6-Y-3-indolyl)-4-oxobutanoic acid with an appropriate 1-R₂ -2-R₃-5/6-Y₁ -indole.

In a second of its process aspects, the invention relates to a processfor preparing the 3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(3H)-furanoneswhich comprises the ring closing cyclization of an appropriate2,4-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-4-oxobutanoic acid.

In a third of its process aspects, the invention relates to a processfor preparing the 3-Z-4-Z₁ -5-Z₂ -5-(1-R-2-R₁-5/6-Y-3-indolyl)-2(5H)-furanones in which Z is 1-R-2-R₁-5/6-Y-3-indolyl and Z₂ is 1-R₂ -2-R₃ -5/6-Y₁ -3-indolyl which comprisesinteracting the appropriate 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-2(3H)-furanone with an appropriate 1-R₂ -2-R₃ -5/6-Y₁-indole.

In the fourth of its process aspects, the invention relates to a processfor the rearrangement of the double bond in the furanone ring of3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(3H)-furanones to obtain3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(5H)-furanones.

In the fifth of its process aspects, the invention relates to a processfor preparing the 5-(1-R-2-R₁ -5/6-Y-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁-3-indolyl)-3,4-dichloro-2(5H)-furanones which comprises interacting theappropriate 4-(1-R-2-R₁ -5/6-Y-3-indolyl)-2,3-dichloro-4-oxo-2-butenoicacid with an appropriate 1-R₂ -2-R₃ -5/6-Y₁ -indole.

In the sixth of its process aspects, the invention relates to a processfor preparing 4-(1-R-2-R₁-5/6-Y-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acids which comprisesinteracting dichloromaleic anhydride with an appropriate 1-R-2-R₁-5/6-Y-indole.

In the seventh of its process aspects, the invention relates to aprocess for preparing 3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃-5/6-Y₁ -3-indolyl)-2(5H)-furanones in which R=R₂, R₁ =R₃ and Y=Y₁ whichcomprises interacting maleic anhydride with the appropriate substituted1-R-2-R₁ -5/6-Y-indole.

In still another aspect, the invention relates to pressure-sensitivecarbonless duplicating systems and/or to thermal marking systems whichcontain any of the above-mentioned -3-Z-4-Z₁ -5-Z₂ -5-(1-R-2-R₁-5/6-Y-3-indolyl)-2(5H)-furanones or 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-2(3H)-furanones represented by Formulas I and II,respectively.

DETAILED DESCRIPTION INCLUSIVE OF THE PREFERRED EMBODIMENTS

More specifically, this invention, in one of its composition of matteraspects relating to the final products, resides in the novelindolyl-substituted 2-furanones, which are particularly useful ascolorless precursors in the art of carbonless duplicating, and which areselected from the group consisting of 3-Z-4-Z₁ -5-Z₂ -5-(1-R-2-R₁-5/6-Y-3-indolyl)-2(5H)-furanones having the formula ##STR1## and3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(3H)-furanones having the formula##STR2## wherein Z when Z₁ is chlorine and at least one of Z₂ and R isother than hydrogen, represents chlorine, or when Z₁ is hydrogen,represents a monovalent 1-R-2-R₁ -5/6-Y-3-indolyl moiety of the formula##STR3## Z₁ represents hydrogen or when Z is chlorine and at least oneof Z₂ and R is other than hydrogen, represents chlorine; Z₂ representshydrogen or a monovalent 1-R₂ -2-R₃ -5/6-Y₁ -3-indolyl moiety of theformula ##STR4## R and R₂ represent hydrogen, non-tertiary alkyl of oneto eight carbon atoms, alkenyl of two to four carbon atoms, benzyl orbenzyl substituted in the benzene ring by one or two of halo or alkyl ofone to three carbon atoms; R₁ and R₃ represent hydrogen, alkyl of one tothree carbon atoms or phenyl; and Y and Y₁ represent one or two ofhydrogen, alkyl of one to three carbon atoms, alkoxy of one to threecarbon atoms, halo or nitro.

In addition to being final products, the 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-2(3H)-furanones of Formula II also form one of thecomposition of matter aspects of this invention relating tointermediates.

In a first particular embodiment in accordance with its final productcomposition of matter aspect, the invention sought to be patentedresides in the novel 3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃-5/6-Y₁ -3-indolyl)-2(5H)-furanones of Formula I wherein Z is 1-R-2-R₁-5/6-Y-3-indolyl; Z₁ is hydrogen; and Z₂ is 1-R₂ -2-R₃ -5/6-Y₁-3-indolyl. Preferred compounds within the ambit of this particularembodiment are of the formula ##STR5## wherein R, R₁, R₂, R₃, Y and Y₁have the same respective meanings given in relation to Formula I.

In a second particular embodiment in accordance with its final productcomposition of matter aspect, the invention sought to be patentedresides in the novel 3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(5H)-furanonesof Formulas I wherein Z is 1-R-2-R₁ -5/6-Y-3-indolyl; and Z₁ and Z₂ areeach hydrogen. Preferred compounds within the ambit of this particularembodiment are of the formula ##STR6## wherein R, R₁ and Y have the samerespective meanings given in relation to Formula I.

In a third particular embodiment in accordance with its final productcomposition of matter aspect, the invention sought to be patentedresides in the novel 5-(1-R-2-R₁ -5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁-3-indolyl)-3,4-dichloro-2(5H)-furanones of Formula I wherein Z and Z₁are each chlorine; and Z₂ is 1-R₂ -2-R₃ -5/6-Y₁ -3-indolyl. Preferredcompounds within the ambit of this particular embodiment are of theformula ##STR7## wherein R, R₁, R₂, R₃, Y and Y₁ have the samerespective meanings given in relation to Formula I.

In a fourth particular embodiment in accordance with its final productcomposition of matter aspect, the invention sought to be patentedresides in the novel 5-(1-R-2-R₁-5/6-Y-3-indolyl)-3,4-dichloro-2(5H)-furanones of Formula I wherein Zand Z₁ are each chlorine; and Z₂ is hydrogen. Preferred compounds withinthe ambit of this particular embodiment are of the formula ##STR8##wherein R, R₁ and Y have the same respective meanings given in relationto Formula I.

In a fifth particular embodiment in accordance with its final productcomposition of matter aspect, the invention sought to be patentedresides in the novel 3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(3H)-furanonesof Formula II wherein R, R₁ and Y each have the same respective meaningsindicated in relation to Formula II.

This invention, in a second of its composition of matter aspects,relating to intermediates, resides in the novel 2,4-bis(1-R-2-R₁-5/6-Y-3-indolyl)-4-oxobutanoic acids which are useful as intermediatesto the final products and having the formula ##STR9## wherein Rrepresents hydrogen, non-tertiary alkyl of one to eight carbon atoms,alkenyl of two to four carbon atoms, benzyl or benzyl substituted in thebenzene ring by one or two of halo or alkyl of one to three carbonatoms; R₁ represents hydrogen, alkyl of one to three carbon atoms orphenyl; Y represents one or two of hydrogen, alkyl of one to threecarbon atoms, alkoxy of one to three carbon atoms, halo or nitro; andwith the proviso that R cannot be hydrogen or methyl when R₁ is methyland Y is hydrogen.

This invention, in a third of its composition of matter aspects,relating to intermediates, resides in the novel 4-(1-R-2-R₁-5/6-Y-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acids, which are usefulas intermediates to the final product and having the formula ##STR10##wherein R represents hydrogen, non-tertiary alkyl of one to eight carbonatoms, alkenyl of two to four carbon atoms, benzyl or benzyl substitutedin the benzene ring by one or two of halo or alkyl of one to threecarbon atoms; R₁ represents hydrogen, alkyl of one to three carbon atomsor phenyl; and Y represents one or two hydrogen, alkyl of one to threecarbon atoms, alkoxy of one to three carbon atoms, halo or nitro.

In one of its process aspects, the invention sought to be patentedresides in the process for the preparation of the novel 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁ -3-indolyl)-2(5H)-furanones ofFormula III and also represented by Formula I in which Z is 1-R-2-R₁-5/6-Y -3-indolyl; Z₁ is hydrogen; and Z₂ is 1-R₂ -2-R₃ -5/6-Y₁-3-indolyl which comprises interacting an appropriate 2,4-bis(1-R-2-R₁-5/6-Y-3-indolyl)-4-oxobutanoic acid with approximately one molecularproportion of an appropriate 1-R₂ -2-R₃ -5/6-Y₁ -indole wherein R, R₁,R₂, R₃, Y and Y₁ have the same respective meanings indicated in FormulaIII.

In a second process aspect, the invention sought to be patented residesin the process for the preparation of the novel 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-2(3H)-furanones represented by Formula II whichcomprises the ring closing cyclization of an appropriate2,4-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-4-oxobutanoic acid of Formula VIIwherein R, R₁ and Y have the same respective meanings indicated inFormula VII.

In a third process aspect, the invention sought to be patented residesin the process for the preparation of the novel 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁ -3-indolyl)-2(5H)-furanones ofFormula III and also represented by Formula I in which Z is 1-R-2-R₁-5/6-Y-3-indolyl and Z₂ is 1-R₂ -2-R₃ -5/6-Y₁ -3-indolyl which comprisesinteracting the appropriate 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-2(3H)-furanone with approximately one molecularproportion of an appropriate 1-R₂ -2-R₃ -5/6-Y₁ -indole wherein R, R₁,R₂, R₃, Y and Y₁ have the same respective meanings given in relation toFormula III.

In a fourth process aspect, the invention sought to be patented residesin the process for the preparation of the novel 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-2(5H)-furanones represented by Formula IV by therearrangement of the double bond in the furanone ring of3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(3H)-furanones wherein R, R₁ and Yhave the same respective meanings indicated in Formula IV.

In a fifth process aspect, the invention sought to be patented residesin the process for the preparation of the novel 5-(1-R-2-R₁-5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁-3-indolyl)-3,4-dichloro-2(5H)-furanones represented by Formula V whichcomprises interacting an appropriate 4-(1-R-2-R₁-5/6-Y-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid with approximatelyone molecular proportion of an appropriate 1-R₂ -2-R₃ -5/6-Y₁ -indolewherein R, R₁, R₂, R₃, Y and Y₁ have the same respective meaningsindicated in Formula V.

In a sixth process aspect, the invention sought to be patented residesin the process for the preparation of the novel 4-(1-R-2-R₁-5/6-Y-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acids represented byFormula VIII which comprises interacting an appropriate 1-R-2-R₁-5/6-Y-indole with approximately one molecular proportion ofdichloromaleic anhydride wherein R, R₁ and Y have the same respectivemeanings indicated in Formula VIII.

In a seventh process aspect, the invention sought to be patented residesin the process for the preparation of the novel 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁ -3-indolyl)-2(5H)-furanonesrepresented by Formula III which comprises interacting maleic anhydridewith approximately one to approximately three molecular proportions ofan appropriate 1-R-2-R₁ -5/6-Y-indole wherein R=R₂ R₁ =R₃ and Y=Y₁ andhave the same respective meanings indicated in Formula III.

As used herein, the term "non-tertiary alkyl of one to eight carbonatoms" means saturated monovalent aliphatic radicals, including branchedchain radicals, for example, methyl, ethyl, propyl, isopropyl, butyl,isobutyl, amyl, 1-methylbutyl, 3-methylbutyl, hexyl, isohexyl, heptyl,isoheptyl, octyl, isooctyl and 2-ethylhexyl.

As used herein, the term "alkenyl of two to four carbon atoms" means amonovalent aliphatic radical possessing a single double bond, forexample, ethenyl (or vinyl), 2-propenyl (or allyl), 1-methylethenyl (orisopropenyl), 2-methyl-2-propenyl, 2-methyl-1-propenyl, 2-butenyl and3-butenyl.

When the terms "alkyl of one to three carbon atoms" and "alkoxy of oneto three carbon atoms" are used herein, there is meant saturated,acyclic groups which may be straight or branched as exemplified bymethyl, ethyl, propyl, isopropyl, methoxy, ethoxy, propoxy orisopropoxy.

When the term "halo" is used herein, there are included chloro, fluoro,bromo and iodo. The preferred halo substituent is chloro because theother halogens offer no particular advantages over chloro and because ofthe relatively low cost and ease of preparation of the required chlorointermediates. However, the other above-named halo substituents are alsosatisfactory.

The novel compounds represented by Formulas I and II above areessentially colorless in the depicted lactone form. When the compoundsof Formula I, bearing two or three indole substituents, and those ofFormula II are contacted with an acidic medium, for example, silica gelor one of the types regularly employed in pressure-sensitive carbonlessduplicating systems, for example, silton clay or phenolic resins, theydevelop a colored image of good to excellent tinctorial strength. Theprompt development of color on contact with silica gel, silton clay or aphenolic resin demonstrates that these compounds are highly suitable foruse as colorless precursors, that is, color-forming substances inpressure-sensitive carbonless duplicating systems. For such application,the compounds may be incorporated in any of the commercially acceptedsystems known in the carbonless duplicating art. A typical technique forsuch application is as follows. Solutions of the colorless precursorcompounds in suitable aromatic solvents are microencapsulated bywell-known procedures. The microcapsules are coated on the reverse sideof a transfer sheet with the aid of a suitable binder and the coatedtransfer sheet is then assembled in a manifold with the microcapsulecoated side in contact with a receiving sheet coated with an electronaccepting substance, for example, silton clay or a phenolic resin.Application of pressure to the manifold such as that exerted by astylus, typewriter or other form of writing or printing causes thecapsules on the reverse side to rupture. The solution of the colorformer released from the ruptured microcapsules flows to the receivingsheet and on contact with the acidic medium thereon promptly forms abluish-green to reddish-purple colored image of good tinctorialstrength. It is, of course, obvious that variants of this mode ofapplication can be utilized. For example, the receiving sheet in amanifold can alternatively be coated with the subject compounds and theacidic developing agent can be contained in microcapsules applied to thereverse side of the top sheet in the manifold.

It has also been found that when the compounds of Formulas I and II areintimately mixed with an acidic developer of the type generally employedin thermal papers, that is, papers which produce a colored image whencontacted with a heated stylus or heated type, for example, bisphenol A,heating of the mixture produces a colored image of varying shades fromgreen-blue to purple depending on the particular compound of theinvention employed. The ability of the compounds of Formulas I and II toreadily form a deep color when heated in admixture with an acidicdeveloper such as bisphenol A, makes them useful in thermal papermarking systems, either where an original or a duplicate copy isprepared by contacting the thermal paper with a heated stylus or heatedtype in any of the methods generally known in the art.

As stated above, the compounds of Formula I are useful as colorprecursors, particularly in the art of carbonless duplicating systems.As with other colorless precursors currently in use in the art, thecompounds are colorless under neutral or basic conditions, but becomecolored when contacted with an acidic material such as silica gel, aphenolic resin or an acidic clay. It is frequently desired that theimages produced by such color precursors by copiable by xerographicmeans. A widely used color precursor is3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide or, as thiscompound has been more simply designated, crystal violet lactone.Crystal violet lactone produces a blue image which is intense but whichsuffers the disadvantage of being poorly copiable by xerographic means.To counteract this disadvantage, other color precursors have been mixedwith crystal violet lactone as described, for example, in U.S. Pat. No.3,525,630. The images produced by the compounds of Formula I, which aregenerally equal or greater in intensity of color than images produced bycrystal violet lactone, are readily copiable by xerographic means. Forthis reason, the difficulties inherent in using mixed color precursorsto achieve xerographic copiability can be avoided by using a compound ofFormula I above.

The colored images produced by development of the compounds of FormulaI, either by thermal means or by contact with acidic material have beenfound to possess good to excellent light stability on exposure todaylight or to a daylight fluorescent lamp.

In view of the utility of the final products as described above, anotheraspect of this invention resides in pressure-sensitive carbonlessduplicating systems and thermal paper marking systems containing as acolor-forming substance any of the 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-2(3H)-furanones depicted by Formula II; the3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁-3-indolyl)-2(5H)-furanones depicted by Formula III; the3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(5H)-furanones represented byFormula IV; and the 5-(1-R-2-R₁ -5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁-3-indolyl)-3,4-dichloro-2(5H)-furanones represented by Formula Vwherein R, R₁, R₂, R₃, Y and Y₁ have the same respective meanings givenin relation to Formulas II, III, IV and V.

The compounds of Formula I in which Z and Z₁ are both chlorine and Z₂ ishydrogen have also been found to produce colored images in brown toblack shades when paper treated with them without an acid developer iscontacted with a heated stylus or heated type. This group of compoundsof the invention are decidedly advantageous over those compoundsemployed in thermal duplicating systems which require the incorporationof an acidic developer such as bisphenol A in that they afford thermalcopy systems containing only a single component for the production of acolored image. Thus, in another of its aspects, this invention residesin a thermal paper marking system containing as a color formingsubstance a 5-(1-R-2-R₁ -5/6-Y-3-indolyl)-3,4-dichloro-2(5H)-furanonehaving the structural formula ##STR11## in which R is hydrogen,non-tertiary alkyl of one to eight carbon atoms, alkenyl of two to fourcarbon atoms, benzyl or benzyl substituted in the benzene ring by one ortwo of halo or alkyl of one to three carbon atoms; R₁ representshydrogen, alkyl of one to three carbon atoms or phenyl; and Y representsone or two of hydrogen, alkyl of one to three carbon atoms, alkoxy ofone to three carbon atoms, halo or nitro.

The best mode contemplated by the inventors of carrying out thisinvention will now be described so as to enable any person skilled inthe art to which it pertains to make and use the same.

The compounds of Formulas I and II are prepared by a variety ofprocesses. More specifically, the 3,5,5-tris-indolyl-substitutedcompounds represented by Formula III, which fall within the scope ofthose depicted in Formula I, are prepared by interacting approximatelyan equimolar quantity of the appropriate 2,4-bis(1-R-2-R₁-5/6-Y-3-indolyl)-4-oxobutanoic acid with the appropriate 1-R₂ -2-R₃-5/6-Y₁ -indole. The reaction is conveniently carried out in adehydrating solvent, for example, acetic anhydride preferably in thepresence of oxygen at a temperature in the range of 10° to 100° C, butmore desirably, at a temperature in the range of 20° to 75° C. The3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁-3-indolyl)-2(5H)-furanone thus obtained can be isolated if desired,either by filtration from the reaction medium or alternatively byextraction into and subsequent isolation from an aromatic organicsolvent, for example, benzene or toluene. In the latter method, thereaction medium is slowly combined with a mixture of the aromaticorganic solvent, water, ice and sufficient alkali, for example, ammoniaor sodium hydroxide to render the mixture slightly alkaline. The organiclayer is separated and dried over a suitable drying agent and thenfiltered. There is added to the clear solution a suitablecoprecipitating inert organic solvent, for example, hexane or apetroleum ether which causes the product to be precipitated or tocrystallize from the solution. The separated final product is thencollected and dried by conventional means.

In a second and alternative preparative method, the3,5,5-tris-indolyl-substituted compounds of Formula III can beconveniently obtained by interacting the appropriate 3,5-bis(1-R-2-R₁-5/6-Y-3-indolyl)-2(3H)-furanone of Formula II with approximately anequimolar quantity of an appropriate 1-R₂ -2-R₃ -5/6-Y₁ -indole. Thisreaction is also carried out in a dehydrating solvent, for example,acetic anhydride preferably in the presence of oxygen and at atemperature in the range of 10° to 100° C, but more desirably, at atemperature in the range of 20° to 75° C to obtain the desired3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁-3-indolyl)-2(5H)-furanone of Formula III. The product is isolated in amanner similar to that indicated in the process described above.

The 3,5,5-tris-indolyl-substituted compounds of Formula III in which theindole moieties are the same can be prepared by interacting maleicanhydride with approximately two molecular proportions of theappropriate 1-R-2-R₁ -5/6-Y-indole. The reaction is conveniently carriedout in a dehydrating solvent, for example, acetic anhydride preferablyin the presence of oxygen at a temperature in the range of 10° to 140°C, but more desirably, at a temperature in the range of 75° C to 140° Cto obtain the desired 3,5,5-tris(1-R-2-R₁-5/6-Y-3-indolyl)-2(5H)-furanones of Formula III. The final products areisolated in a manner similar to that indicated in the first mode ofsynthesis described above. Although the stoichiometry of this reactioncalls for three molecular proportions of the indole for one of maleicanhydride, it has been found that more satisfactory yields and betterquality of the product are obtained when an excess of maleic anhydrideis present, as is the case when less than three molecular proportionsare employed.

The 2(3H)-furanones of Formula II are useful as final products as wellas intermediates to the 2(5H)-furanones and are conveniently prepared bythe cyclization of an appropriate 2,4-bis(1-R-2-R₁-5/6-Y-3-indolyl)-4-oxobutanoic acid to the corresponding3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(3H)-furanone. The cyclization isconveniently carried out in a dehydrating solvent, for example, aceticanhydride preferably in the presence of oxygen at a temperature in therange of 10° to 50° C, but more desirably, at a temperature in the rangeof 20° to 30° C to obtain the desired product of Formula II. The finalproduct is isolated by filtration.

The 3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(5H)-furanone compoundsrepresented by Formula IV are conveniently prepared by rearrangement ofthe double bond in the furanone ring of the corresponding3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(3H)-furanones. The reaction iseffected by heating the appropriate3,5-bis(indolyl)-substituted-2(3H)-furanone in a dehydrating solvent,for example, acetic anhydride preferably in the presence of oxygen at atemperature in the range of 40° to 100° C, but more desirably, at atemperature in the range of 50° to 70° C to obtain the desired3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-2(5H)-furanones which areconveniently isolated by filtration.

The final products represented by Formula V, which are 5-(1-R-2-R₁-5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁-3-indolyl)-3,4-dichloro-2(5H)-furanones, are conveniently prepared byinteracting the appropriate 4-(1-R-2-R₁-5/6-Y-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid with approximatelyan equimolar quantity of an appropriate 1-R₂ -2-R₃ -5/6-Y₁ -indole. Thereaction is conveniently carried out in a dehydrating solvent, forexample, acetic anhydride preferably in the presence of oxygen at atemperature in the range of 10° to 100° C, but more desirably, at atemperature in the range of 20° to 30° C to obtain the desired5-(1-R-2-R₁ -5/6-Y-3-indolyl)-5-(1-R₂ -2-R₃ -5/6-Y₁-3-indolyl)-3,4-dichloro-2(5H)-furanone. These final products areisolated either by filtration from the reaction medium or by drowningthe reaction mixture in a mixture of water, ice and sufficient alkali,for example, ammonia to render the drowned mixture slightly alkaline.The separated product is then collected by filtration.

The 5-(1-R-2-R₁ -5/6-Y-3-indolyl)-3,4-dichloro-2(5H)-furanone compoundsrepresented by Formula VI are conveniently prepared by the methoddescribed by Rees and Sabet in the Journal of the Chemical Society,687-691 (1965) which comprises condensing commercially availablemucochloric acid with an appropriate indole.

The 2,4-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-4-oxobutanoic acids, representedby Formula VII, which are required for the preparation of the finalproducts of Formulas II, III and IV, are conveniently prepared accordingto the procedure of Diels and Alder, Ann. Chem. 490, 277-294 (1931),comprising the condensation of maleic anhydride with approximately twomolar equivalents of an appropriate 1-R-2-R₁ -5/6-Y-indole.

The 4-(1-R-2-R₁ -5/6-Y-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acidsrepresented by Formula VIII, which are required for the preparation ofthe final products of Formula V are conveniently prepared by interactingcommercially available dichloromaleic anhydride with approximately anequimolar quantity of an appropriate 1-R-2-R₁ -5/6-Y-indole. Thereaction is carried out in an inert organic solvent, for example,ethylene dichloride at a temperature in the range of 10° to 100° C, butpreferably in the temperature range of 10° to 30° C to obtain thedesired 2-butenoic acids of Formula VIII which are isolated byfiltration.

It has been found that in the above-described preparative procedures forobtaining the final products which involve a keto-acid, whether as astarting material per se or generated in situ, it is desirable tointroduce oxygen, preferably in the form of air during the reaction. Theprecise role of oxygen in these reactions is not understood at thistime; but it is observed that substantially improved yields of the finalproducts obtained through the keto-acid intermediates are obtained whenoxygen is present during the reaction period. Although various modes ofintroducing oxygen into the reaction mixtures can be employed, forexample, by the use of hydrogen peroxide, it has been found thatentirely satisfactory results are obtained by incorporating air into thereaction mixture. This is conveniently accomplished by any of severalconventional techniques, for example, by rapid agitation of the reactionmixture, by passing a stream of air over the reaction mixture or bybubbling air into the mixture by means of a gas dispersion device.

Indole and the substituted indoles required as intermediates for thepreparation of the keto-acid intermediates of Formulas VII and VIII andfor the final products of Formulas I, II, III, V and VI form an old andwell-known class of compounds which are readily obtained by conventionalprocedures well known in the art. The following compounds are exemplaryof indoles useful in the practice of this invention.

Indole,

1-Methylindole,

2-Methylindole,

1,2-Dimethylindole,

1-Ethyl-2-methylindole,

2-Phenylindole,

1-Propyl-2-methylindole,

1-Benzyl-2-methylindole,

1-Butyl-2-methylindole,

1-Octyl-2-methylindole,

2-Ethyl-5-methylindole,

1-Benzyl-5-fluoroindole,

1-Methyl-6-nitroindole,

5-Methoxy-1-butylindole,

1-Allyl-2-methylindole,

1,2-Dimethyl-6-nitroindole,

1-(4-Chlorobenzyl)-2-methyl-5-nitroindole,

1-Methyl-5-bromo-6-nitroindole,

2,5,6-Trimethylindole,

1-Isobutyl-2-methylindole,

6-Bromo-2-methylindole,

1-Hexylindole,

1-(2,5-Dimethylbenzyl)-2-methylindole,

2-Propylindole,

6-Chloro-2-phenylindole,

1-(2-Ethylhexyl)-2-methylindole,

1-(2,6-Dichlorobenzyl)-2-methylindole,

1-Vinyl-2-methylindole,

2-Ethyl-6-methylindole,

6-Fluoro-1-benzylindole,

1-(4-Bromobenzyl)-2-isopropylindole,

1-(3-Chlorobenzyl)-2-ethylindole,

5-Chloro-1-benzylindole,

1-(2-Fluorobenzyl)-2-methylindole,

5-Iodo-1-(1-methylhexyl)indole,

5,6-Dimethoxyindole,

1-(2-Methylbenzyl)-2-methylindole,

5,6-Dichloro-2-phenylindole,

1-Isoamylindole, and

1-[3-(2-Methyl)-1-propenyl]-2-methylindole.

The molecular structures of the compounds of the invention were assignedon the basis of the modes of synthesis and study of their infrared,nuclear magnetic resonance and mass spectra.

The following examples will further illustrate the invention without,however, limiting it thereto. All melting points are uncorrected.

EXAMPLE 1

A. A stirred solution of 20.0 g (0.204 mole) of maleic anhydride and70.0 g (0.408 mole) of 1-n-propyl-2-methylindole in 200 ml of benzenewas heated at reflux for a period of approximately eighteen hours andthen allowed to cool to ambient temperature. The solid which separatedfrom the cooled solution was collected by filtration, washed with freshchilled benzene and dried in vacuo at 60° C to obtain 30.0 g of2,4-bis(1-n-propyl-2-methyl-3-indolyl)-4-oxobutanoic acid (Formula VII:R═CH₃ CH₂ CH₂ ; R₁ ═CH₃ ; Y═H) as a white solid melting over the range210° to 215° C.

Infrared maxima appeared at 1695 (C═O; s ) and 1638 (C═O; s) cm⁻¹. Thenuclear magnetic resonance spectrum was in agreement with the assignedstructure. Analysis by mass spectrum showed m/e peaks at 444(M⁺) and at400(M⁺ -CO₂).

B. A stirred mixture of 7.0 g (0.0157 mole) of the2,4-bis(1-n-propyl-2-methyl-3-indolyl)-4-oxobutanoic acid prepared asdescribed in A above, 2.7 g (0.017 mole) of 1-ethyl-2-methylindole, 100ml of acetic anhydride and 1.0 ml of glacial acetic acid was aerated bybubbling air through the mixture for approximately eight hours at atemperature in the range of 48°-52° C. The solid that formed wascollected by filtration. A second crop of product was obtained bydrowning the filtrate in a stirred mixture of ice, benzene andsufficient concentrated ammonia hydroxide to make the mixture slightlyalkaline. The benzene layer was separated, dried over molecular sieves,filtered and the filtrate set aside for several hours. The crystals,which separated from the solution, were collected by filtration andcombined with the first crop of product. The combined solids were driedin vacuo at 60° C to obtain3,5-bis(1-n-propyl-2-methyl-3-indolyl)-5-(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═CH₃ CH₂ CH₂ ; R₁ ═R₃ ═CH₃ ; R₂ ═CH₃ CH₂ ; Y═Y₁ ═H) as atan solid which decomposed at 179° C.

A significant infrared maximum appeared at 1745 (C═O; s) cm⁻¹. Thenuclear magnetic resonance spectrum was in complete agreement with theassigned structure. Analysis by mass spectrum showed m/e peaks at569(M⁺) and at 525(M⁺ -CO₂).

A benzene solution of the product spotted on silica gel, an acidic clayor a phenolic resin develops a deep blue-colored image which has goodxerographic copiability and good lightfastness.

C. Following a procedure similar to that described above in part A ofthis example by using 6-bromo-2-methylindole instead of1-n-propyl-2-methylindole, there is obtained2,4-bis(6-bromo-2-methyl-3-indolyl)-4-oxobutanoic acid (Formula VII:R═H; R₁ ═CH₃ ; Y═6-Br).

D. Following a procedure similar to that described above in part B ofthis example except that2,4-bis(6-bromo-2-methyl-3-indolyl)-4-oxobutanoic acid is used in placeof 2,4-bis(1-n-propyl-2-methyl-3-indolyl)-4-oxobutanoic acid, there isobtained3,5-bis(6-bromo-2-methyl-3-indolyl)-5-(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═Y₁ ═H; R₁ ═R₃ ═CH₃ ; R₂ ═CH₃ CH₂ ; Y═6-Br).

E. When 6-chloro-2-phenylindole is substituted for1-n-propyl-2-methylindole in part A of this example, there is obtained2,4-bis(6-chloro-2-phenyl-3-indolyl)-4-oxobutanoic acid (Formula VII:R═H; R₁ ═C₆ H₅ ; Y═6-Cl).

F. Following a procedure similar to that described above in part B ofthis example by using 2,4-bis(6-chloro-2-phenyl-3-indolyl)-4-oxobutanoicacid instead of 2,4-bis(1-n-propyl-2-methyl-3-indolyl)-4-oxobutanoicacid, and 2-propylindole is substituted for 1-ethyl-2-methylindole,there is obtained3,5-bis(6-chloro-2-phenyl-3-indolyl)-5-(2-propyl-3-indolyl)-2(5H)-furanone(Formula III: R═R₂ ═Y₁ ═H; R₁ ═C₆ H₅ ; R₃ ═CH₃ CH₂ CH₂ ; Y═6-Cl).

EXAMPLE 2

A. A stirred mixture of 7.1 g (0.016 mole) of2,4-bis(1-n-propyl-2-methyl-3-indolyl)-4-oxobutanoic acid (prepared asdescribed in Example 1, part A), 2.8 g (0.016 mole) of1-n-propyl-2-methyl-indole, 100 ml of acetic anhydride and 1.0 ml ofglacial acetic acid was heated under an atmosphere of air atapproximately 60° C for a period of approximately sixteen hours. Theresultant solution was then cooled to 10° C by means of an ice bath. Thesolid which separated from the solution was collected by filtration anddried in vacuo at 60° C. A second crop of product was obtained bydrowning the filtrate in a stirred mixture of ice, benzene andsufficient concentrated ammonium hydroxide to make the mixture slightlyalkaline. The benzene layer was separated, dried over molecular sievesand filtered. Approximately three volumes of n-hexane was slowly stirredinto the clear benzene solution which was then evaporated at ambienttemperature in a fume hood to approximately one-half of its originalvolume. The crystals which separated from the solution were collected byfiltration and dried in vacuo at 60° C and combined with the first crop.There was thus obtained3,5,5-tris(1-n-propyl-2-methyl-3-indolyl)-2(5H)-furanone (Formula III:R═R₂ ═CH₃ CH₂ CH₂ ; R₁ ═R₃ ═CH₃ ; Y═Y₁ ═H) as a light tan solid whichsoftened at 82° C and melted with decomposition at 96° C.

A significant infrared maximum appeared at 1755 (C═O; s) cm⁻¹. Thenuclear magnetic resonance spectrum was in accord with the assignedstructure. Analysis by mass spectrum showed m/e peaks at 597(M⁺) and at553(M⁺ -CO₂).

A benzene solution of the product spotted on silica gel, an acidic clayor a phenolic resin develops a deep blue-colored image which has goodxerographic copiability and good lightfastness.

B. Following a procedure similar to that described above in part A ofthis example except that2,4-bis(6-chloro-2-phenyl-3-indolyl)-4-oxobutanoic acid is used in placeof 2,4-bis(1-n-propyl-2-methyl-3-indolyl)-4-oxobutanoic acid and6-chloro-2-phenylindole is used instead of 1-n-propyl-2-methylindole,there is obtained 3,5,5-tris(6-chloro-2-phenyl-3-indolyl)-2(5H)-furanone(Formula III: R═R₂ ═H; R₁ ═R₃ ═C₆ H₅ ; Y═Y₁ ═6-Cl).

EXAMPLE 3

A. A stirred mixture of 160.0 g (0.97 mole) of 1-ethyl-2-methylindole(95 percent assay), 40.0 g (0.408 mole) of maleic anhydride and 700 mlof benzene was heated at reflux for a period of approximately eighteenhours and then cooled to ambient temperature. The separated solid wascollected by filtration and dried in vacuo at 60° C to obtain 52.4 g of2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoic acid (Formula VII:R═CH₃ CH₂ ; R₁ ═CH₃ ; Y═H), a white solid melting over the range of221°-225° C.

Upon analysis by infrared, maxima appeared at 1705 (C═O; s) and 1642(C═O; s) cm⁻¹. Analysis by mass spectrum showed m/e peaks at 416(M⁺) andat 372(M⁺ -CO₂).

B. A mixture of 2.9 g (0.007 mole) of2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoic acid prepared asdescribed in Part A above, 4.0 g (0.0236 mole) of 1-ethyl-2-methylindole(94 percent assay) and 50 ml of acetic anhydride was stirred forapproximately twenty-four hours under an atmosphere of air at ambienttemperature. The separated solid was collected by filtration and driedin vacuo at 60° C to obtain as a yellow-white powder3,5,5-tris(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone (Formula III: R═R₂═CH₃ CH₂ ; R₁ ═R₃ ═CH₃ ; Y═Y₁ ═H), a white solid which melted at231°-232° C.

Infrared spectral analysis showed a maximum at 1745 (C═O, s) cm⁻¹. Thenuclear magnetic resonance spectrum was concordant with the assignedstructure. Mass spectral analysis showed m/e peaks at 555(M⁺) and at511(M⁺ -CO₂).

A benzene solution of the product when spotted on silica gel, an acidicclay or a phenolic resin develops a dark blue-violet-colored image. Thedeveloped image has good xerographic copiability and good lightfastness.

C. When 1-(4-chlorobenzyl)-2-methyl-5-nitroindole is substituted for1-ethyl-2-methylindole in part A of this example, there is obtained2,4-bis[1-(4-chlorobenzyl)-2-methyl-5-nitro-3-indolyl]-4-oxobutanoicacid (Formula VII: R═4-ClC₆ H₄ CH₂ ; R₁ ═CH₃ ; Y═5-NO₂).

D. Following a procedure similar to that described above in part B ofthis example by using2,4-bis[1-(4-chlorobenzyl)-2-methyl-5-nitro-3-indolyl]-4-oxobutanoicacid instead of 2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoic acidand 1-(4-chlorobenzyl)-2-methyl-5-nitroindole is substituted for1-ethyl-2-methylindole, there is obtained3,5,5-tris[1-(4-chlorobenzyl)-2-methyl-5-nitro-3-indolyl]-2(5H)-furanone(Formula III: R═R₂ ═4-ClC₆ H₄ CH₂ ; R₁ ═R₃ ═CH₃ ; Y═Y₁ ═5-NO₂).

EXAMPLE 4

A. A mixture of 40.0 g (0.096 mole) of2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoic acid (prepared as inExample 3, part A) and 450 ml of acetic anhydride was stirredapproximately seventeen hours at ambient temperature under an atmosphereof air. The solid that formed was collected by filtration and washedfirst with acetic anhydride and then with diethyl ether. After drying at60° C in vacuo there was obtained 34.0 g of3,5-bis(1-ethyl-2-methyl-3-indolyl)-2(3H)-furanone (Formula II: R═CH₃CH₂ ; R₁ ═CH₃ ; Y═H) as a white solid which melted over the range186°-188° C with decomposition.

Infrared analysis showed maxima at 1645 (C═C; m) and 1805 (C═O; s) cm⁻¹.Nuclear magnetic resonance analysis was in accord with the assignedstructure. Mass spectral analysis showed m/e peaks at 398(M⁺) and 354(M⁺-CO₂).

An acetone solution of the product spotted on silica gel, an acidic clayor a phenolic resin develops a turquoise-colored image.

B. A mixture of 5.5 g (0.0138 mole) of3,5-bis(1-ethyl-2-methyl-3-indolyl)-2(3H)-furanone, 8.0 g (0.05 mole) of1-ethyl-2-methylindole, 100 ml of acetic anhydride and 0.25 ml of 30percent hydrogen peroxide was stirred approximately eighteen hours atroom temperature. The solid was collected by filtration and a smallsample showed an infrared maximum at 1800 cm⁻¹ and a smaller maximum at1745 cm⁻¹. The solid and the filtrate were recombined, and stirredeighteen hours at approximately 60° C. The solid was collected byfiltration and dried at 60° C in vacuo to obtain3,5,5-tris(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone (Formula III: R═R₂═CH₃ CH₂ ; R₁ ═R₃ ═CH₃ ; Y═Y₁ ═H) as a white solid which melted at232°-234° C.

A significant infrared maximum appeared at 1745 (C═O; s) cm⁻¹. Thenuclear magnetic resonance spectrum was concordant with the assignedstructure. Mass spectral analysis showed m/e peaks at 555(M⁺) and 511(M⁺-CO₂).

When a benzene solution of the product was spotted on silica gel, anacidic clay or a phenolic resin, it developed a deep blue-colored imagewhich has good xerographic copiability and good lightfastness.

Analysis of this product demonstrates it to be identical with thatobtained in Example 3, part B above.

C. Following a procedure similar to that described above in part A ofthis example except that2,4-bis(6-fluoro-1-benzyl-3-indolyl)-4-oxobutanoic acid prepared byinteraction of maleic anhydride and 6-fluoro-1-benzylindole by aprocedure similar to that described in Example 3, part A is used inplace of 2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoic acid, thereis obtained 3,5-bis(6-fluoro-1-benzyl-3-indolyl)-2(3H)-furanone (FormulaII: R═C₆ H₅ CH₂ ; R₁ ═H; Y═6-F).

D. When 3,5-bis(6-fluoro-1-benzyl-3-indolyl)-2(3H)-furanone issubstituted for 3,5-bis(1-ethyl-2-methyl-3-indolyl-2(3H)-furanone and5,6-dimethoxyindole is substituted for 1-ethyl-2-methylindole in theprocedure described in part B of this example, there is obtained3,5-bis(6-fluoro-1-benzyl-3-indolyl)-5-(5,6-dimethoxy-3-indolyl)-2(5H)-furanone(Formula III: R═C₆ H₅ CH₂ ; R₁ ═R₂ ═R₃ ═H; Y═6-F; Y₁ ═5,6-(CH₃ O)₂).

EXAMPLE 5

A. A stirred mixture of 2.25 g (0.023 mole) of maleic anhydride, 8.0 g(0.50 mole) of 1-ethyl-2-methylindole and 2.71 g of acetic anhydride washeated at reflux in an atmosphere of air for approximately thirtyminutes, then cooled slightly below the reflux temperature and anadditional 2.71 g of acetic anhydride were added. The reaction mixturewas heated at reflux for an additional seventy minutes in the presenceof air before cooling to room temperature. A portion of the thick,tar-like reaction mixture was dissolved in benzene and treated withsufficient dilute aqueous ammonia to render the mixture slightlyalkaline. The benzene layer was separated and hexane slowly added to thesolution causing a blue-gray solid to separate. The solid was collectedby filtration and dried at 40° C in vacuo to obtain3,5,5-tris(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone (Formula III: R═R₂═CH₃ CH₂ ; R₁ ═R₃ ═CH₃ ; Y═Y₁ ═H) as a pale blue-gray powder whichmelted over the range 232°-234° C.

Infrared spectral analysis gave a significant maxima at 1750 (C═O; s)cm⁻¹. The assigned structure was corroborated by a concordant nuclearmagnetic resonance spectrum.

A benzene solution of the product spotted on silica gel, an acidic clayor a phenolic resin develops a deep blue-colored image which has goodxerographic copiability and good lightfastness.

The product obtained in this example was found upon analysis to beidentical to the products obtained in part B of Examples 3, part B and4, part B.

B. Following a procedure similar to that described above in part A ofthis example by using 2-ethyl-6-methylindole instead of1-ethyl-2-methylindole, there is obtained3,5,5-tris(2-ethyl-6-methyl-3-indolyl)-2(5H)-furanone (Formula III: R═R₂═H; R₁ ═R₃ ═CH₃ CH₂ ; Y═Y₁ ═6-CH₃).

C. Following a procedure similar to that described above in part A ofthis example except that 1-isoamylindole is used in place of1-ethyl-2-methylindole, there is obtained3,5,5-tris(1-isoamyl-3-indolyl)-2(5H)-furanone (Formula III: R═R₂═(CH₃)₂ CHCH₂ CH₂ ; R₁ ═R₃ ═Y═Y₁ ═H).

D. When 1-vinyl-2-methylindole is substituted for 1-ethyl-2-methylindolein part A of this example, there is obtained3,5,5-tris(1-vinyl-2-methyl-3-indolyl)-2(5H)-furanone (Formula III: R═R₂═CH₂ ═CH; R₁ ═R₃ ═CH₃ ; Y═Y₁ ═H).

E. Following a procedure similar to that described above in part A ofthis example by using 1-(2-methylbenzyl)-2-methylindole instead of1-ethyl-2-methylindole, there is obtained3,5,5-tris[1-(2-methylbenzyl)-2-methyl-3-indolyl]-2(5H)-furanone(Formula III: R═R₂ ═2-CH₃ -C₆ H₄ CH₂ ; R₁ ═R₃ ═CH₃ ; Y═Y₁ ═H).

F. Following a procedure similar to that described above in part A ofthis example except that 5-iodo-1-(1-methylhexyl)-indole is used inplace of 1-ethyl-2-methylindole, there is obtained3,5,5-tris[5-iodo-1-(1-methylhexyl)-3-indolyl]-2(5H)-furanone (FormulaIII: R═R₂ ═CH₃ (CH₂)₄ CH(CH₃); R₁ ═R₃ ═H; Y═Y₁ ═5-I).

EXAMPLE 6

A stirred mixture of 16.8 g (0.0403 mole) of2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoic acid (prepared asdescribed in Example 3, part A), 8.0 g (0.0427 mole) of1-n-butyl-2-methyl-indole, 400 ml of acetic anhydride and 4.0 ml ofglacial acetic acid was heated at approximately 60° C for approximatelyeighteen hours in an atmosphere of air. The resulting solution wascooled to ambient temperature and slowly added with stirring to amixture of ice, benzene and sufficient concentrated ammonium hydroxideto render the mixture slightly alkaline. The benzene layer wasseparated, dried over molecular sieves and filtered. To the driedbenzene filtrate there was slowly added with stirring an equal volume ofn-hexane. The solid which slowly separated was collected by filtrationand dried in vacuo at 60° C to obtain3,5-bis(1-ethyl-2-methyl-3-indolyl)-5-(1-n-butyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═CH₃ CH₂ ; R₁ ═R₃ ═CH₃ ; R₂ ═CH₃ (CH₂)₂ CH₂ ; Y═Y₁ ═H) asa tan solid which melted at 98° C with decomposition.

A significant infrared maximum appeared at 1755 (C═O; s) cm⁻¹. Theassigned structure was corroborated by a concordant nuclear magneticresonance spectrum. Mass spectral analysis showed m/e peaks at 555(M⁺)and at 511(M⁺ -CO₂).

A benzene solution of the product applied to silica gel, an acidic clayor a phenolic resin develops a blue-colored image which has goodxerographic copiability and good lightfastness.

EXAMPLE 7

A. A mixture of 20.0 g (0.048 mole) of2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoic acid (prepared asdescribed in Example 3, part A) and 300 ml of acetic anhydride wasstirred at room temperature (25° C) for approximately eighteen hours.The solid that formed was collected by filtration and dried in vacuo at60° C to obtain 3,5-bis(1-ethyl-2-methyl-3-indolyl)-2(3H)-furanone(Formula II: R═CH₃ CH₂ ; R₁ ═CH₃ ; Y═H) as a white solid melting at186°-188° C with decomposition.

Upon infrared spectral analysis, significant maxima were found at1645(C-C; m) and at 1805 (C═O; s) cm⁻¹.

B. A mixture of 6.4 g (0.016 mole) of3,5-bis(1-ethyl-2-methyl-3-indolyl)-2(3H)-furanone prepared as describedin part A directly above, 2.8 g (0.016 mole) of 1-n-propyl-2-methylindole, 100 ml of acetic anhydride and 2.0 ml of glacial acetic acid wasstirred and aerated by bubbling air through the mixture forapproximately sixteen hours at ambient temperature and then at atemperature of approximately 50° C for twenty-four hours. The resultingmixture was cooled to room temperature and the solid which separated wascollected by filtration and dried in vacuo at 60° C to obtain3,5-bis(1-ethyl-2-methyl-3-indolyl)-5-(1-n-propyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═CH₃ CH₂ ; R₁ ═R₃ ═CH₃ ; R₂ ═CH₃ CH₂ CH₂ ; Y═Y₁ ═H) as atan solid which melted over the range 203° to 206° with decomposition.

Infrared analysis showed a maximum at 1745 (C═O; s) cm⁻¹. The nuclearmagnetic resonance analysis was in accord with the assigned structure.Mass spectral analysis showed m/e peaks at 569(M⁺) and at 525(M⁺ -CO₂).

When a benzene solution of the product is spotted on silica gel, anacidic clay or a phenolic resin a dark blue-colored image develops. Thedeveloped image demonstrates good xerographic copiability and goodlightfastness.

EXAMPLE 8

Following a procedure similar to that described in Example 3, part B,4.2 g (0.0101 mole) of 2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoicacid prepared as described in Example 3, part A was interacted with 1.5g (0.0104 mole) of 1,2-dimethylindole to obtain 2.0 g of3,5-bis(1-ethyl-2-methyl-3-indolyl)-5-(1,2-dimethyl-3-indolyl)-2(5H)-furanone(Formula III: R═CH₃ CH₂ ; R₁ ═R₂ ═R₃ ═CH₃ ; Y═Y₁ ═H) as a white solidmelting at 227°-228° C.

An infrared maximum appeared at 1750 (C═O; s) cm⁻¹. The nuclear magneticresonance spectrum was concordant with the assigned structure. Massspectral analysis gave a m/e peak at 497(M⁺ -CO₂).

A toluene solution of the product when spotted on silica gel, an acidicclay or a phenolic resin develops a dark blue-colored image which hasgood xerographic copiability and good lightfastness.

EXAMPLE 9

Following a procedure similar to that described in Example 3, part B,4.2 g (0.0101 mole) of 2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoicacid (prepared as described in Example 3, part A) was interacted with1.3 g (0.010 mole) of 2-methylindole to obtain3,5-bis(1-ethyl-2-methyl-3-indolyl)-5-(2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═CH₃ CH₂ ; R₁ ═R₃ ═CH₃ ; R₂ ═Y═Y₁ ═H), a paleblue-colored product which melted over the range of 232°-236° C withdecomposition.

A significant infrared maximum appeared at 1728 (C═0; s) cm⁻¹. Thenuclear magnetic resonance spectrum was in complete agreement with theassigned structure. Mass spectral analysis gave m/e peaks at 527(M⁺) and483(M⁺ -CO₂).

When a benzene solution of the product was spotted on silica gel, anacidic clay or a phenolic resin it developed a dark blue-colored imagewhich has good xerographic copiability and good lightfastness.

EXAMPLE 10

A. A stirred solution of 90.0 g (0.686 mole) of 2-methylindole, 30.0 g(0.306 mole) of maleic anhydride, 350 ml of benzene and 5.0 ml ofglacial acetic acid was heated at reflux under a nitrogen atmosphere fora period of approximately sixty-five hours. The resulting slurry wascooled to approximately 60° C and the solid was collected by filtration,washed with approximately 100 ml of benzene that had been heated toapproximately 60° C. After drying to a constant weight of 29.7 g invacuo at 60° C there was obtained2,4-bis(2-methyl-3-indolyl)-4-oxobutanoic acid (Formula VII: R═Y═H; R₁═CH₃) as a pale yellow solid which melted at 217°-218° C withdecomposition.

Infrared maxima appeared at 1630 (C═0; m) and 1692 (C═0; s) cm⁻¹. Thenuclear magnetic resonance spectrum was concordant with the assignedstructure. Mass spectral analysis showed m/e peaks at 360(M⁺) and 316(M⁺-CO₂).

B. Employing a procedure similar to that described in Example 3, part Babove, but interacting 2.7 g (0.0075 mole) of2,4-bis(2-methyl-3-indolyl)-4-oxobutanoic acid and 1.3 g (0.01 mole) of2-methylindole in place of the2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoic acid and1-ethyl-2-methylindole, respectively, there was obtained3,5,5-tris(2-methyl-3-indolyl)-2(5H)-furanone (Formula III: R═R₂ ═Y═Y₁═H; R₁ ═R₃ ═CH₃), a pale blue powder which melted at 133°-135° C withdecomposition.

Significant infrared maxima appeared at 1735 (C═0; s) and 3400 (N-H; w)cm⁻¹. Nuclear magnetic resonance analysis were in accord with theassigned structure. The mass spectrum showed a m/e peak at 427(M⁻ -CO₂).

A benzene solution of the product spotted on silica gel, an acidic clayor a phenolic resin developed a deep purple-colored image which has goodxerographic copiability and good lightfastness.

EXAMPLE 11

Following a procedure similar to that described in Example 3, part B,but interacting 3.6 g (0.01 mole) of2,4-bis(2-methyl-3-indolyl)-4-oxobutanoic acid, prepared as described inExample 10, part A above and 2.0 g (0.0138 mole) of 1,2-dimethylindole,there was obtained 1.2 g of3,5-bis(2-methyl-3-indolyl)-5-(1,2-dimethyl-3-indolyl)-2(5H)-furanone(Formula III: R═Y═Y₁ ═H; R₁ ═R₂ ═R₃ ═CH₃) as a faint blue-colored powderwhich melted in the range of 207°-227° C.

Upon analysis by infrared, maxima appeared at 1730 (C═0; s) and 3400(N-H; w) cm⁻¹. The nuclear magnetic resonance spectrum was concordantwith the assigned structure. Analysis by mass spectrum showed m/e peaksat 485(M⁺) and 441(M⁺ -CO₂).

A benzene solution of the product when spotted on silica gel, an acidicclay or a phenolic resin develops a deep grape-colored image. Thedeveloped image has good xerographic copiability and good lightfastness.

EXAMPLE 12

Employing a procedure similar to that described in Example 3, part Babove, for interacting 3.6 g (0.01 mole) of2,4-bis(2-methyl-3-indolyl)-4-oxobutanoic acid prepared as described inExample 10, part A and 1.98 g (0.0125 mole) of 1-ethyl-2-methylindole,there was obtained3,5-bis(2-methyl-3-indolyl)-5-(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═Y═Y₁ ═H; R₁ ═R₃ ═CH₃ ; R₂ ═CH₃ CH₂) as a light brownpowder which melted in the range 176°-181° C.

Significant infrared maxima appeared at 1730 (C═0; s) and 3400 (N-H; w)cm⁻¹. The nuclear magnetic resonance spectrum was in complete agreementwith the assigned structure. Mass spectral analysis showed a m/e peak at455(M⁺ -CO₂).

When a toluene solution of the product is applied to silica gel, anacidic clay or a phenolic resin, it develops a deep grape-colored imagewhich has good xerographic copiability and good lightfastness.

EXAMPLE 13

Following a procedure similar to that described in Example 3, part Babove, 3.6 g (0.01 mole) of 2,4-bis(2-methyl-3-indolyl)-4-oxobutanoicacid (described above in Example 10, part A) and 2.12 g (0.01 mole) of2-phenylindole were interacted to obtain 0.26 g of3,5-bis(2-methyl-3-indolyl)-5-(2-phenyl-3-indolyl)-2(5H)-furanone(Formula III: R═R₂ ═Y═Y₁ ═H; R₁ ═CH₃ ; R₃ ═C₆ H₅), a pale blue-coloredpowder which melted in the range of 204°-215° C.

Significant infrared maxima appeared at 1710 (C═0; s) and 3400 (N-H; w)cm⁻¹. Nuclear magnetic resonance analysis was in accord with theassigned structure. Analysis by mass spectrum showed a m/e peak at358(M⁺ -carbon dioxide-2-methylindolyl moiety).

A benzene solution of the product spotted on silica gel, an acidic clayor phenolic resin develops a deep blue-colored image which has goodxerographic copiability and good lightfastness.

EXAMPLE 14

Following a procedure similar to that described above in Example 6, 5.5g (0.016 mole) of 2,4-bis(2-methyl-3-indolyl)-4-oxobutanoic acidprepared as described in Example 10, part A above and 3.3 g (0.016 mole)of 1-n-octyl-2-methylindole were interacted with aeration to obtain 6.0g of3,5-bis(2-methyl-3-indolyl)-5-(1-n-octyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═Y═Y₁ ═H; R₁ ═R₃ ═CH₃ ; R₂ ═CH₃ (CH₂)₆ CH₂), a pale bluepowder which decomposed at 134° C.

Significant infrared maxima appeared at 1730 (C═0; s) and 3395 (N-H; w)cm⁻¹. Nuclear magnetic resonance analysis was in accord with theassigned structure. Analysis by mass spectrum showed a m/e peak at539(M⁺ -CO₂).

When a benzene solution of the product is spotted on silica gel, anacidic clay or a phenolic resin, a deep blue-colored image developswhich has good xeographic copiability and good lightfastness.

EXAMPLE 15

Proceeding in a manner similar to Example 6 above, 5.5 g (0.016 mole) of2,4-bis(2-methyl-3-indolyl)-4-oxobutanoic acid prepared as described inExample 10, part A above and 3.0 g (0.016 mole) of 1-allyl-2-methylindole were interacted and aerated to obtain3,5-bis(2-methyl-3-indolyl)-5-(1-allyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═Y═Y₁ ═H; R₁ ═R₃ ═CH₃ ; R₂ ═ CH₂ ═CHCH₂) as acream-colored solid which melted over the range of 150°-174° C withdecomposition.

The infrared spectrum showed maxima at 1730 (C═0; s) and 3380 (N-H; w)cm⁻¹. The nuclear magnetic resonance spectrum was concordant with theassigned structure. Mass spectral analysis showed a m/e peak at 467(M⁺-CO₂).

A benzene solution of the product when spotted on silica gel, an acidicclay or a phenolic resin develops a deep blue-colored image which hasgood xerographic copiability and good lightfastness.

EXAMPLE 16

Following a procedure similar to that described in Example 2 above, 5.5g (0.016 mole) of 2,4-bis(2-methyl-3-indolyl)-4-oxobutanoic acidprepared as described in Example 10, part A above and 3.6 g (0.016 mole)of 1-benzyl-2-methylindole were interacted to obtain3,5-bis(2-methyl-3-indolyl)-5-(1-benzyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═Y═Y₁ ═H; R₁ ═R₃ ═CH₃ ; R₂ ═C₆ H₅ CH₂) as a tan solidwhich melted over the range 170°-180° C with decomposition.

Infrared spectral analysis showed a maximum at 1740 (C═0; s) cm⁻¹. Thenuclear magnetic resonance spectrum was concordant with the assignedstructure. Mass spectral analysis showed a m/e peak at 517(M⁺ -CO₂).

An acetone solution of the product when spotted on silica gel, an acidicclay or a phenolic resin develops a blue-colored image. The developedimage exhibits good xerographic copiability.

EXAMPLE 17

Proceeding in a manner similar to that described above in Example 6, 5.5g (0.016 mole) of 2,4-bis(2-methyl-3-indolyl)-4-oxobutanoic acidprepared as described in Example 10, part A above and 3.0 g (0.016 mole)of 1-n-butyl-2-methylindole were interacted to obtain3,5-bis(2-methyl-3-indolyl)-5-(1-n-butyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═Y═Y₁ ═H; R₁ ═R₃ ═CH₃ ; R₂ ═CH₃ (CH₂)₂ CH₂), a pale bluepowder which melted over the range of 180°-184° C with decomposition.

A significant infrared maximum appeared at 1730 (C═0; s) cm⁻¹. Thenuclear magnetic resonance spectrum corroborated the assigned structure.Mass spectral analysis showed a m/e peak at 483(M⁺ -CO₂).

An acetone solution of the product applied to silica gel, an acidic clayor a phenolic resin develops a deep blue-colored image which has goodxerographic copiability and good lightfastness.

EXAMPLE 18

A. A stirred mixture of 30.0 g (0.2 mole) of 1,2-dimethylindole, 10.0 g(0.10 mole) of maleic anhydride, 170 ml of toluene and 0.5 ml of glacialacetic acid was heated at reflux temperature for approximately seventeenhours. After cooling to ambient temperature, the solid was collected byfiltration and washed on the filter with a small portion of freshtoluene. The toluene wet solid was suspended with stirring in benzene,warmed to approximately 60° C and filtered. The collected white crystalswere dried at 60° C in vacuo to obtain 16.0 g of2,4-bis(1,2-dimethyl-3-indolyl)-4-oxobutanoic acid (Formula VII: R═R₁═CH₃ ; Y═H) which melted over the range of 243°-245° C.

Upon infrared spectral analysis, maxima appeared at 1645 (C═0; m) and1695 (C═0; s) cm⁻¹. Mass spectral analysis showed a m/e peak at 344(M⁺-CO₂).

B. Following a procedure similar to that described above in Example 3,part B, 3.8 g (0.02 mole) of2,4-bis(1,2-dimethyl-3-indolyl)-4-oxobutanoic acid (prepared in part Aabove) and 2.0 g (0.02 mole) of 1,2-dimethylindole were interacted toobtain 1.5 g of 3,5,5-tris(1,2-dimethyl-3-indolyl)-2(5H)-furanone(Formula III: R═R₁ ═R₂ ═R₃ ═CH₃ ; Y═Y₁ ═H) as a white solid which meltedin the range of 232° to 234° C.

A significant infrared maximum appeared at 1750 (C═0; s) cm⁻¹. Thenuclear magnetic resonance spectrum was concordant with the assignedstructure. Analysis by mass spectrum gave m/e peaks at 513(M⁺) and469(M⁺ -CO₂).

A toluene solution of the product when spotted on silica gel, an acidicclay or a phenolic resin develops a deep blue-colored image which hasgood xerographic copiability and good lightfastness.

EXAMPLE 19

Proceeding in a manner similar to that described above in Example 3,part B, 3.8 g (0.012 mole) of2,4-bis(1,2-dimethyl-3-indolyl)-4-oxobutanoic acid prepared as describedin Example 18, part A above and 2.0 g (0.012 mole) of1-ethyl-2-methylindole were interacted to obtain3,5-bis(1,2-dimethyl-3-indolyl-5-(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═R₁ ═R₃ ═CH₃ ; R₂ ═CH₃ CH₂ ; Y═Y₁ ═H) as a paleblue-colored powder which melted over the range 191°-194° C.

A significant infrared meximum appeared at 1745 (C═0; s) cm⁻¹. Thenuclear magnetic resonance spectrum was concordant with the assignedstructure. Analysis by mass spectrum showed m/e peaks at 527(M⁺) and483(M⁺ -CO₂).

An acetone solution of the product when spotted on silica gel, an acidicclay or a phenolic resin develops a deep blue-colored image which hasgood xerographic copiability and good lightfastness.

EXAMPLE 20

A. Following a procedure similar to that described above in Example 1,part A, 54.0 g (0.190 mole) of 1-n-butyl-2-methylindole and 19.0 g(0.095 mole) of maleic anhydride was interacted to obtain 26.0 g of2,4-bis(1-n-butyl-2-methyl-3-indolyl)-4-oxobutanoic acid (Formula VII:R═CH₃ (CH₂)₂ CH₂ ; R₁ ═CH₃ ; Y═H) as a pale blue-white solid whichmelted over the range of 203° to 205° C. An infrared maximum wasobserved at 1700 (C═O; s) cm⁻¹.

B. Proceeding in a manner similar to that described above in Example 3,part B, 7.3 g (0.016 mole) of2,4-bis(1-n-butyl-2-methyl-3-indolyl)-4-oxobutanoic acid (prepared inpart A directly above) and 2.1 g (0.016 mole) of 2-methylindole wasinteracted to obtain3,5-bis(1-n-butyl-2-methyl-3-indolyl)-5-(2-methyl-3-indolyl-2(5H)-furanone(Formula III: R═CH₃ (CH₂)₂ CH₂ ; R₁ ═R₃ ═CH₃ ; R₂ ═Y═Y₁ ═H) as a paleblue-colored solid which melted over the range of 175°-180° C withdecomposition.

An infrared maxima appeared at 1730 (C═O; s) cm⁻¹. Nuclear magneticresonance analysis was in accord with the assigned structure. Analysisby mass spectrum showed a m/e peak at 539(M⁺ -CO₂).

An acetone solution of the product spotted on silica gel, an acidic clayor a phenolic resin develops a deep blue-colored image which has goodxerographic copiability and good lightfastness.

EXAMPLE 21

A mixture of 7.6 g (0.016 mole) of2,4-bis(1-butyl-2-methyl-3-indolyl)-4-oxobutanoic acid, prepared asdescribed in Example 20, part A above, 3.0 g (0.016 mole) of1-n-butyl-2-methylindole, 100 g of acetic anhydride and 1.0 ml ofglacial acetic acid was stirred and aerated, by bubbling air through themixture, at approximately 60° C for a period of twenty hours. The aceticanhydride and acetic acid were removed from the mixture by distillationat reduced pressure yielding a syrup-like material which was thendissolved in benzene and treated with a sufficient quantity of diluteaqueous ammonia to render the mixture slightly alkaline. The benzenelayer was separated and to it there was slowly added hexane causing athick, tar-like substance to settle out of the solution. The tar-likematerial was redissolved in benzene and to the solution there was addedhexane which again caused a tar-like solid to separate. After settingapproximately eighteen hours in the mixed solvent system the tar-likesolid gave way to a friable solid material. The product was collected byfiltration and dried at 60° C in vacuo to obtain3,5,5-tris(1-n-butyl-2-methyl-3-indolyl)-2(5H)-furanone (Formula III:R═R₂ ═CH₃ (CH₂)₂ CH₂ ; R₁ ═R₃ ═CH₃ ; Y═Y₁ ═H), a pale brown-coloredsolid which melted over the range 111° to 146° C.

A significant infrared maximum was observed at 1755 (C═O; s) cm⁻¹. Thenuclear magnetic resonance spectrum was consistent with the assignedstructure.

A benzene solution of the product spotted on silica gel, an acidic clayor a phenolic resin develops a deep blue-colored image. The developedimage has good xerographic copiability and good lightfastness.

EXAMPLE 22

A. A mixture of 8.0 g (0.019 mole) of2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoic acid prepared asdescribed in Example 3, part A, and 100 ml of acetic anhydride wasstirred approximately seventeen hours under an atmosphere of air atambient temperature. The solid was filtered and washed first with freshacetic anhydride and then with diethyl ether to obtain3,5-bis(1-ethyl-2-methyl-3-indolyl)-2(3H)-furanone (Formula II: R═C₂ H₅; R₁ ═CH₃ ; Y═H) as a white solid which melted over the range 186°-188°C with decomposition.

A significant infrared maximum appeared at 1805 (C═O; s) cm⁻¹. Thenuclear magnetic resonance spectrum was concordant with the assignedstructure.

When a benzene solution of the product is applied to silica gel, anacidic clay or a phenolic resin, a turquoise image develops.

B. The (3H) isomer obtained in A above was converted to the (5H) isomerby the following procedure. The solid from part A above and the filtratefrom part A above were combined with stirring at approximately 60° C inthe presence of air for a period of approximately seventeen hours. Themixture was then cooled to room temperature and the resultant solid wascollected by filtration and washed first with small portions of freshacetic anhydride and then with diethyl ether. At this point, theinfrared spectral analysis showed no shift in the value for the carbonylband. The solid and the reaction filtrate were recombined and stirred at75° C under an atmosphere of air for approximately fifteen hours. Uponcooling to ambient temperature, the solid was collected by filtration,washed with small portions of fresh acetic anhydride and diethyl etherand dried at 60° C in vacuo to obtain3,5-bis(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone (Formula IV: R═CH₃CH₂ ; R₁ ═CH₃ ; Y═H) as a white solid which melted at 213°-214° C withdecomposition.

A significant infrared maximum appeared at 1762 (C═O; s) cm⁻¹. Thenuclear magnetic resonance spectrum was in complete agreement with theassigned structure. Mass spectral analysis showed m/e peaks at 398(M⁺)and 354(M⁺ -CO₂).

An acetone solution of the product spotted on silica gel, an acidic clayor a phenolic resin develops a turquoise-colored image.

C. Following a procedure similar to that described above in part A ofthis example by using 2,4-bis(2,5,6-trimethyl-3-indolyl)-4-oxobutanoicacid (prepared by the interaction of maleic anhydride and2,5,6-trimethylindole in a manner similar to that described in Example3, part A) instead of 2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoicacid, there is obtained3,5-bis(2,5,6-trimethyl-3-indolyl)-2(3H)-furanone (Formula II: R═H; R₁═CH₃ ; Y═5,6-(CH₃)₂).

D. When 3,5-bis(2,5,6-trimethyl-3-indolyl)-2(3H)-furanone is substitutedfor 3,5-bis(1-ethyl-2-methyl-3-indolyl)-2(3H)-furanone in part B of thisexample, there is obtained3,5-bis(2,5,6-trimethyl-3-indolyl)-2(5H)-furanone (Formula IV: R═H; R₁═CH₃ ; Y═5,6-(CH₃)₂).

E. Following a procedure similar to that described above in part A ofthis example except that2,4-bis[1-(4-bromobenzyl)-2-isopropyl-3-indolyl]-4-oxobutanoic acid(prepared by the interaction of maleic anhydride and1-(4-bromobenzyl)-2-isopropylindole in a similar manner to thatdescribed in Example 3, part A) is used in place of2,4-bis(1-ethyl-2-methyl-3-indolyl)-4-oxobutanoic acid, there isobtained 3,5-bis[1-(4-bromobenzyl)-2-isopropyl-3-indolyl]-2(3H)-furanone(Formula II: R═4-BrC₆ H₄ CH₂ ; R₁ ═(CH₃)₂ CH; Y═H).

F. Substituting3,5-bis[1-(4-bromobenzyl)-2-isopropyl-3-indolyl]-2(3H)-furanone for 3,5L-bis(1-ethyl-2-methyl-3-indolyl)-2(3H)-furanone in the proceduredescribed in part B above in this example, there is obtained3,5-bis[1-(4-bromobenzyl)-2-isopropyl-3-indolyl]-2(5H)-furanone (FormulaIV: R═4-BrC₆ H₄ CH₂ ; R₁ ═(CH₃)₂ CH; Y═H).

EXAMPLE 23

A. Proceeding in a manner similar to that described above in Example 4,part A, 8.0 g (0.02 mole) of2,4-bis(1,2-dimethyl-3-indolyl)-4-oxobutanoic acid prepared as describedin Example 18, part A above was interacted with 100 ml of aceticanhydride to obtain 3,5-bis(1,2-dimethyl-3-indolyl)-2-(3H)-furanone(Formula II: R═R₁ ═CH₃ ; Y═H) as a white solid.

The significant infrared maxima were at 1645 (C═C; m) and 1785 (C═O; s)cm⁻¹.

An acetone solution of the product when spotted on silica gel, an acidicclay or a phenolic resin develops a turquoise color.

B. The (3H) isomer obtained in A above was converted to the (5H) isomerby the following procedure. The solid and filtrate from part A of thisexample were recombined and stirred at approximately 60° C for a periodof approximately seventeen hours in the presence of air, and then atapproximately 75° C for a period of approximately fifteen hours. Thesolid in the mixture was collected by filtration, washed with a smallportion of fresh acetic anhydride and dried at 60° C in vacuo to obtain3,5-bis(1,2-dimethyl-3-indolyl)-2-(5H)-furanone (Formula IV: R═R₁ ═CH₃ ;Y═Y₁ ═H) as a tan solid which melted over the range of 238°-241° C withdecomposition.

Infrared spectral analysis showed a maximum at 1762 (C═O; s) cm⁻¹. Thenuclear magnetic resonance spectrum was concordant with the assignedstructure.

An acetone solution of the product when spotted on silica gel, an acidicclay or a phenolic resin develops a turquoise-colored image.

C. Following a procedure similar to that described above in part A ofthis example by using2,4-bis{1-[3-(2-methyl)-1-propenyl]-2-methyl-3-indolyl}-4-oxobutanoicacid (prepared by interacting maleic anhydride and1-[3-(2-methyl)-1-propenyl]-2-methylindole in a manner similar to thatdescribed in Example 18, part A) instead of2,4-bis(1,2-dimethyl-3-indolyl)-4-oxobutanoic acid, there is obtained3,5-bis{1-[3-(2-methyl)-1-propenyl]-2-methyl-3-indolyl}-2(3H)-furanone(Formula II: R═CH₂ ═CH(CH₃)CH₂ ; R₁ ═CH₃ ; Y═H).

D. Following a procedure similar to that described above in part B ofthis example except that3,5-bis{1-[3-(2-methyl)-1-propenyl]-2-methyl-3-indolyl}-2(3H)-furanoneis used in place of 3,5-bis(1,2-dimethyl-3-indolyl)-2-(3H)-furanone,there is obtained3,5-bis{1-[3-(2-methyl)-1-propenyl]-2-methyl-3-indolyl}-2(5H)-furanone(Formula IV: R═CH₂ ═CH (CH₃)CH₂ ; R₁ ═CH₃ ; Y═H).

E. When 3,5-bis(6-fluoro-1-benzyl-3-indolyl)-2(3H)-furanone issubstituted for 3,5-bis(1,2-dimethyl-3-indolyl)-2(3H)-furanone in part Bof this example, there is obtained3,5-bis-(6-fluoro-1-benzyl-3-indolyl)-2(5H)-furanone (Formula IV: R═C₆H₅ CH₂ ; R₁ ═H; Y═6-F).

F. Following a procedure similar to that described above in part A ofthis example by using 2,4-bis(6-chloro-2-phenyl-3-indolyl)-4-oxabutanoicacid instead of 2,4-bis(1,2-dimethyl-3-indolyl)-4-oxobutanoic acid,there is obtained 3,5-bis(6-chloro-2-phenyl-3-indolyl)-2(3H)-furanone(Formula II: R═H; R₁ ═C₆ H₅ ; Y═6-Cl).

G. Following a procedure similar to that described above in part B ofthis example except that3,5-bis(6-chloro-2-phenyl-3-indolyl)-2(3H)-furanone is used in place of3,5-bis(1,2-dimethyl-3-indolyl-2(3H)-furanone, there is obtained 3,5-bis(6 chloro-2-phenyl-3-indolyl)-2(5H)-furanone (Formula IV: R═H; R₁ ═C₆ H₅; Y═6-Cl).

When 2,4-bis(1-n-butyl-5-methoxy-3-indolyl)-4-oxobutanoic acid (preparedby interacting 1-n-butyl-5-methoxyindole and maleic anhydride in amanner similar to that described in Example 18, part A) is substitutedfor 2,4-bis(1,2-dimethyl-3-indolyl)-4-oxobutanoic acid in part A of thisexample, there is obtained3,5-bis(1-n-butyl-5-methoxy-3-indolyl)-2(3H)-furanone (Formula II: R═CH₃(CH₂)2 CH₂ ; R₁═ H, Y═5-CH₃ 0).

I. Following a procedure similar to that described above in part B ofthis example by using3,5-bis(1-n-butyl-5-methoxy-3-indolyl)-2(3H)-furanone instead of3,5-bis(1,2-dimethyl-3-indolyl)-2-(3H)-furanone, there is obtained3,5-bis(1-n-butyl-5-methoxy-3-indolyl)-2-(5H)-furanone (Formula IV:R═CH₃ (CH₂)2 CH₂ ; R₁ ═H; Y═5-CH₃ 0).

EXAMPLE 24

A. A mixture of 10.0 g (0.07 mole) of 1,2-dimethylindole, 12.0 g (0.07mole) of dichloromaleic anhydride and 200 ml of ethylene dichloride wasstirred at ambient temperature for approximately eighteen hours. Thesolid present in the reaction mixture was collected by filtration. Afterdrying at 60° C in vacuo there was obtained 20.0 g of4-(1,2-dimethyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid (FormulaVIII: R═R₁ ═CH₃ ; Y═H) as a pale blue solid which melted over the range150° to 153° C. Infrared spectral analysis showed a maximum at 1712(C═0; s) cm⁻¹.

B. A mixture of 2.5 g (0.017 mole) of 1,2-dimethylindole, 5.3 g (0.017mole) of 4-(1,2-dimethyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acidprepared as described in part A directly above and 130 ml of aceticanhydride were stirred at ambient temperature under an atmosphere of airfor approximately thirty-five hours. An additional 1.0 g (0.0069 mole)of 1,2-dimethylindole was added and stirring was continued for anadditional seventeen hours. The solid was collected from the reactionmixture by filtration and dried at 60° C in vacuo. There was thusobtained 5.0 g of5,5-bis(1,2-dimethyl-3-indolyl)-3,4-dichloro-2(5H)-furanone (Formula V:R═R₁ ═R₂ ═R₃ ═CH₃ ; Y═Y₁ ═H), a pale purple-colored solid which did notmelt up to a temperature of 300° C.

Significant infrared maxima appeared at 1628 (C═C; m) and 1762 (C═O; s)cm⁻¹. The nuclear magnetic resonance spectrum was in complete agreementwith the assigned structure. Mass spectral analysis showed a m/e peak at358(M⁺ -CO₂ -HCl).

A toluene solution of the product spotted on silica gel, an acidic clayor a phenolic resin develops a grape-colored image which possessesexcellent xerographic copiability.

C. Following a procedure similar to that described above in part A ofthis example by using 2-ethyl-5-methylindole instead of1,2-dimethylindole, there is obtained4-(2-ethyl-5-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid(Formula VIII: R═H; R₁ ═CH₃ CH₂ ; Y═5-CH₃).

D. Following a procedure similar to that described above in part B ofthis example except that4-(2-ethyl-5-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid isused in place of4-(1,2-dimethyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid and1-benzyl-5-fluoroindole is substituted for 1,2-dimethylindole, there isobtained5-(2-ethyl-5-methyl-3-indolyl)-5-(1-benzyl-5-fluoro-3-indolyl)-3,4-dichloro-2(5H)-furanone(Formula V: R═R₃ ═H; R₁ ═CH₃ CH₂ ; R₂ ═C₆ H₅ CH₂ ; Y═5-CH₃ ; Y₁ ═5-F).

E. When 1-benzyl-5-fluoroindole is substituted for 1,2-dimethylindole inpart A of this example, there is obtained4-(1-benzyl-5-fluoro-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid(Formula VIII: R═C₆ H₅ CH₂ ; R₁ ═H; Y═5-F).

F. Following a procedure similar to that described above in part B ofthis example by using4-(1-benzyl-5-fluoro-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acidinstead of 4-(1,2-dimethyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acidand 1-methyl-6-nitroindole in place of 1,2-dimethylindole, there isobtained5-(1-benzyl-5-fluoro-3-indolyl)-5-(1-methyl-6-nitro-3-indolyl)-3,4-dichloro-2(5H)-furanone(Formula V: R═C₆ H₅ CH₂ ; R₁ ═R₃ ═H; R₂ ═CH₃ ; Y═6-F; Y₁ ═6-NO₂).

EXAMPLE 25

A. Following a procedure similar to that described above in Example 24,part A, 26.8 g (0.16 mole) of dichloromaleic anhydride and 25.6 g (0.16mole) of 1-ethyl-2-methyl indole were interacted to obtain 40.0 g of4-(1-ethyl-2-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid(Formula VIII: R═CH₃ CH₂ ; R₁ ═CH₃ ; Y═H) as a red-blue solid.

Significant infrared maxima appeared at 1725 (C═O, s), 1595 (C═O; m) and1585 (C═C; w) cm⁻¹. The nuclear magnetic resonance spectrum wasconsistant with the assigned structure. Analysis by mass spectrum showedm/e peaks at 325(M⁺) and 289 (M⁺ -HCl).

B. A mixture of 10.0 g (0.047 mole) of4-(1-ethyl-2-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid, 4.0 g(0.030 mole) of 2-methylindole and 150 ml of acetic anhydride wasstirred at ambient temperature in an atmosphere of air for approximatelyseventeen hours and the solid which formed was collected by filtration.After drying in vacuo at 60° C there was obtained5-(1-ethyl-2-methyl-3-indolyl)-5-(2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone(Formula V: R═CH₃ CH₂ ; R₁ ═R₃ ═CH₃ ; R₂ ═Y═Y₁ ═H) as a blue-coloredsolid which melted over the range of 282°-285° C.

Significant infrared maxima appeared at 1623 (C═C; m), 1762 (C═O; s) and3400 (N-H; w) cm⁻¹. Nuclear magnetic resonance analysis was in accordwith the assigned structure. Analysis by mass spectrum showed m/e peaksat 394(M⁺ -CO₂) and 359(M⁺ -CO₂ -Cl).

When a benzene solution of the product is spotted on silica gel, anacidic clay or a phenolic resin, it develops a grape-colored image whichhas excellent xerographic copiability.

C. Following a procedure similar to that described above in part A ofthis example by using 1-allyl-2-methylindole instead of1-ethyl-2-methylindole, there is obtained4-(1-allyl-2-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid(Formula VIII: R═CH₂ ═CHCH₂ ; R₁ ═CH₃ ; Y═H).

D. Following a procedure similar to that described above in part B ofthis example except that4-(1-allyl-2-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid isused in place of4-(1-ethyl-2-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid and1-n-hexylindole is substituted for 2-methylindole, there is obtained5-(1-allyl-2-methyl-3-indolyl)-5-(1-n-hexyl-3-indolyl)-3,4-dichloro-2(5H)-furanone(Formula V: R═ CH₂ ═CHCH₂ ; R₁ ═CH₃ ; R₂ ═CH₃ (CH₂)₄ CH₂ ; R₃ ═Y═Y₁ ═H).

E. When 5-methoxy-1-n-butylindole is substituted for1-ethyl-2-methylindole in part A of this example, there is obtained4-(1-n-butyl-5-methoxy-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid(Formula VIII: R═CH₃ (CH₂)₂ CH₂ ; R₁ ═H; Y═5-CH₃ O).

F. Following a procedure similar to that described above in part B ofthis example by using4-(1-n-butyl-5-methoxy-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acidinstead of 4-(1-ethyl-2-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoicacid and 1-(3-chlorobenzyl)-2-ethylindole is substituted for2-methylindole, there is obtained5-(1-n-butyl-5-methoxy-3-indolyl)-5-[1-(3-chlorobenzyl)-2-ethyl-3-indolyl]-3,4-dichloro-2(5H)-furanone(Formula V: R═CH₃ (CH₂)₂ CH₂ ; R₁ ═Y₁ ═H; R₂ ═3-ClC₆ H₄ CH₂ ; R₃ ═CH₃CH₂ ; Y═5-CH₃ O).

EXAMPLE 26

A. Proceeding in a manner similar to that described above in Example 24,Part A, 6.5 g (0.05 mole) of 2-methylindole and 8.4 g (0.05 mole) ofdichloromaleic anhydride were interacted to obtain4-(2-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid (Formula VIII:R═Y═H; R₁ ═CH₃) as a green-colored solid.

B. Following a procedure similar to that described above in Example 25,part B, 5.0 g (0.017 mole) of4-(2-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid and 2.7 g(0.017 mole) of 1-ethyl-2-methylindole were interacted to obtain5-(2-methyl-3-indolyl)-5-(1-ethyl-2-methyl-3-indolyl)-2,3-dichloro-2(5H)-furanone(Formula V: R═Y═Y₁ ═H; R₁ ═R₃ ═CH₃ ; R₂ ═CH₃ CH₂) as a red-blue solidwhich melted in the range of 282°-285° C.

Upon analysis by infrared, maxima appeared at 1762 (C═O; s) and 3400(N-H; w) cm⁻¹. The nuclear magnetic resonance spectrum was concordantwith the assigned structure. Analysis by mass spectrum showed m/e peaksat 394(M⁺ -CO₂) and 359(M⁺ -CO₂ -Cl).

A benzene solution of the product when spotted on silica gel, an acidicclay or a phenolic resin develops a deep purple-colored image which hasexcellent xerographic copiability.

EXAMPLE 27

A. A mixture of 10.0 g (0.052 mole) of 2-phenylindole, 8.8 g (0.052mole) of dichloromaleic anhydride and 150 ml of ethylene dichloride wasstirred at ambient temperature for approximately 48 hours. The solidthat formed was collected by filtration and dried at 60° C in vacuo toobtain 4-(2-phenyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid(Formula VIII: R═Y═H; R₁ ═C₆ H₅) as a tan-colored solid which meltedover the range 150°-152° C.

Infrared spectral analysis showed a maximum at 1705 (C═O; s) cm⁻¹. Thenuclear magnetic resonance spectrum was consistent with the assignedstructure.

B. A mixture of 7.0 g (0.02 mole) of4-(2-phenyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acid (prepared inpart A above), 3.5 g (0.02 mole of 1-ethyl-2-methylindole and 200 ml ofacetic anhydride was stirred at ambient temperature in an atmosphere ofair for approximately seventeen hours. The pale blue solid that formedwas collected by filtration and dried in vacuo at 60° C to obtain5-(2-phenyl-3-indolyl)-5-(1-ethyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone(Formula V: R═Y═Y₁ ═H; R₁ ═C₆ H₅ ; R₂ ═CH₃ CH₂ ; R₃ ═CH₃) as atan-colored solid which started to sinter at 213° C and was completelymelted at 225° C.

Significant infrared maxima appeared at 1764 (C═O; s) and 3380 (N-H; w)cm⁻¹. The nuclear magnetic resonance spectrum was in complete agreementwith the assigned structure. Mass spectral analysis showed a m/e peak at441(M⁺ -CO₂).

A benzene solution of the product spotted on silica gel, an acidic clayor a phenolic resin develops a deep blue-colored image which hasexcellent xerographic copiability.

EXAMPLE 28

A stirred mixture of 2.0 g (0.006 mole) of4-(1-ethyl-2-methyl-3-indolyl)-2,3-dichloro-4-oxo-2-butenoic acidprepared as described above in Example 25, part A, 1.0 g (0.006 mole) of1-ethyl-2-methylindole and 50 ml of acetic anhydride was warmed to 60° Cto obtain a green-colored solution. The solution was stirred forapproximately eighteen hours at ambient temperature under an atmosphereof air. The resulting blue solution was slowly added to a mixture of iceand sufficient concentrated ammonium hydroxide to render the mixtureslightly alkaline. A solid which slowly separated from the solution wascollected by filtration and slurried in toluene at room temperature. Thepowder-like solid was collected by filtration and dried at 60° C invacuo. There was thus obtained5,5-bis(1-ethyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone (FormulaV: R═R₂ ═CH₃ CH₂ ; R₁ ═R₃ ═CH₃ ; Y═Y₁ ═H) as a pale blue solid whichdecomposed at 157° C.

A significant infrared maximum appeared at 1760 (C═O; s) cm⁻¹. Nuclearmagnetic resonance analysis was in accord with the assigned structure.Analysis by mass spectrum showed m/e peaks at 466(M⁺) and 422(M⁺ -CO₂).

An acetone solution of the product spotted on silica gel, an acidic clayor a phenolic resin develops a deep purple-colored image which hasexcellent xerographic copiability.

EXAMPLE 29

A stirred mixture of 20.3 g (0.12 mole) of mucochloric acid, 14.1 g(0.12 mole) of indole and 125 ml of benzene was heated for approximatelytwenty hours at reflux temperature. The reaction mixture was cooled toambient temperature and a dark brown solid which had separated wascollected by filtration. This solid was purified by two successiverecrystallizations from benzene at approximately 60° C, with the aid ofdecolorizing charcoal. After the second recrystallization, the purifiedproduct was dried at 60° C in vacuo to obtain 5.3 g of the known5-(3-indolyl)-3,4-dichloro-2(5H)-furanone (Formula VI: R═R₁ ═Y═H), apale green-colored solid, which first melted at 174° C, then turnedblack and finally decomposed at 182° C.

Significant infrared maxima appeared at 1629 (C═C; s), 1745 (C═O; s) and3335 (N-H; s) cm⁻¹. The nuclear magnetic resonance spectrum was incomplete agreement with the assigned structure. Mass spectral analysisshowed a m/e peak at 267(M⁺).

An intimately ground mixture of 0.05 g of the product obtained directlyabove and 0.05 g of Bisphenol A, was slowly heated in a test tube. Acolor change from white to red was observed as the mixture melted overthe range 138°-150° C with decomposition.

Proceeding in a manner similar to that described in Example 29, thefollowing 5-(1-R-2-R₁ -5/6-Y-3-indolyl)-3,4-dichloro-2(5H)-furanones ofFormula VI above were prepared by interaction of mucochloric acid andthe appropriate indole.

EXAMPLE 30

5-(2-methyl-3-indolyl)-3,4-dichloro-2-(5H)-furanone (Formula VI: R═Y═H;R₁ ═CH₃), a white solid melting over the range of 175° to 185° C withdecomposition, in intimate admixture with an equal weight of Bisphenol Athermally develops to a deep blue color at 160° C.

EXAMPLE 31

5-(1-ethyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone (Formula VI:R-C₂ H₅ ; R₁ ═CH₃ ; Y═H) was obtained as a white solid melting at122.5°-124° C and thermally develops to a deep blue color at 125° C whenheated in intimate admixture with an equal weight of Bisphenol A.

EXAMPLE 32

5-(1-n-butyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone (FormulaVI: R═CH₃ (CH₂)₂ CH₂ ; R₁ ═CH₃ ; Y═H) was obtained as a white solidmelting at 87°-89° C. This compound thermally develops to a deep bluecolor when an intimate mixture of the compound and an equal weight ofBisphenol A are heated at 140° C.

EXAMPLE 33

5-(1-n-octyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone (FormulaVI: R═CH₃ (CH₂)₆ CH₂ ; R₁ ═CH₃ ; Y═H), a white solid melting at83°-84.5° C, thermally developed to a deep blue color at 140° C whenheated in intimate admixture with an equal weight of Bisphenol A.

EXAMPLE 34

5-(1-allyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone (Formula VI:R═CH₂ ═CHCH₂ ; R₁ ═CH₃ ; Y═H) was obtained as a gray solid which meltsat 108°-110° C with decomposition. This compound thermally developed toa purple-black color at 125° C when heated in intimate admixture with anequal weight of Bisphenol A.

EXAMPLE 35

5-(1-benzyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone (Formula VI:R═CH₂ C₆ H₅ ; R₁ ═CH₃ ; Y═H), a white solid melting at 144°-148° C withdecomposition, thermally developed to a purple-black color at 140° Cwhen heated in intimate admixture with an equal weight of Bisphenol A.

The infrared analysis, nuclear magnetic resonance analyses and massspectral analyses obtained for the products of Examples 30 to 35,inclusive were concordant for the assigned structures given in thoseexamples.

EXAMPLE 36

Following a procedure similar to that described above in Example 29 byusing 2-ethyl-5-methylindole instead of indole, there is obtained5-(2-ethyl-5-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone (Formula VI:R═H; R₁ ═CH₃ CH₂ ; Y═5-CH₃).

EXAMPLE 37

Following a procedure similar to that described above in Example 29except that 1-methyl-5-bromo-6-nitroindole is used in place of indole,there is obtained5-(1-methyl-5-bromo-6-nitro-3-indolyl)-3,4-dichloro-2(5H)-furanone(Formula VI: R═CH₃ ; R₁ ═H; Y═5-Br-6-NO₂).

EXAMPLE 38

When 6-chloro-2-phenylindole is substituted for indole in Example 29hereinabove, there is obtained5-(2-phenyl-6-chloro-3-indolyl)-3,4-dichloro-2(5H)-furanone (Formula VI:R═H; R₁ ═C₆ H₅ ; Y═6-Cl).

EXAMPLE 39

Following a procedure similar to that described above in Example 29 byusing 5-iodo-1-(1-methylhexyl)indole instead of indole, there isobtained5-[5-iodo-1-(1-methylhexyl)-3-indolyl]-3,4-dichloro-2(5H)-furanone(Formula VI: R═CH₃ (CH₂)₄ CH(CH₃); R₁ ═H; Y═5-I).

EXAMPLE 40

Following a procedure similar to that described above in Example 29except that 1-(4-bromobenzyl)-2-isopropylindole is used in placed ofindole, there is obtained5-[1-(4-bromobenzyl)-2-isopropyl-3-indolyl]-3,4-dichloro-2(5H)-furanone(Formula VI: R═4-BrC₆ H₄ CH₂ ; R₁ ═(CH₃)₂ CH; Y═H).

EXAMPLE 41

The use of the compounds of Formulas II through V and described inExamples 1 through 28 as color forming components in pressure sensitivemicroencapsulated copying systems is illustrated with reference to theproduct of Example 7.

A. A mixture of 196 ml of distilled water and 15.0 g of pigskin gelatinwas stirred at approximately 50° C for approximately 45 minutes. Therewas then added to the mixture a warmed (approximately 50° C) solution of49.0 g of alkylated biphenyls and 1.0 g of3,5-bis(1-ethyl-2-methyl-3-indolyl)-5-(1-n-propyl-2-methyl-3-indolyl)-2(5H)-furanone(Formula III: R═CH₃ CH₂ ; R₁ ═R₃ ═CH₃ ; R₂ ═CH₃ CH₂ CH₂ ; Y═Y₁ ═H),prepared as described above in Example 7. The resulting solution wasstirred for approximately fifteen minutes. A second solution of 81.0 mlof distilled water and 10.0 g of gum arabic was then prepared and warmedto approximately 50° C for approximately one hour.

B. The two solutions, the first containing water, gelatin, alkylatedbiphenyls and the product, and the second containing water and gumarabic were mixed and the pH adjusted to 9 by the addition ofapproximately 0.7 ml of 20 percent aqueous sodium hydroxide. Theresulting mixture was transferred to a larger reactor equipped with avariable speed one-half horsepower Eppenbach Homo-Mixer (Gifford-WoodCo., Hudson, N.Y.) and there was added over a period of two to threeminutes 650 ml of distilled water which had been heated to 50° C. Withthe stirrer running at an applied voltage of between 20 to 25 voltsthere was slowly added sufficient ten percent aqueous acetic acid to setthe pH at 4.5, this being the point where coacervation was initiated.The stirrer speed was increased by raising the applied voltage toapproximately thirty volts and approximately four drops of2-ethylhexanol were added to suppress foaming. After approximatelytwenty minutes, a sample of the suspension was examined microscopicallyand found to have stabilized in the range of 20 to 25 microns particlesize whereupon an external ice/water bath was immediately placed aroundthe reactor containing the suspension. At approximately 20° C, theagitation speed was reduced by decreasing the applied voltage to therange of 20 to 25 volts. Cooling was continued and at approximately 15°C, 10.0 ml of glutaraldehyde was added over a period of five minutes.When the internal temperature reached 10° C, the agitation speed wasfurther reduced by lowering the applied voltage to approximately 20volts and these conditions maintained for approximately thirty minutes.At this time, the Eppenbach Homo-Mixer was replaced with a conventionalblade type laboratory agitator and the suspension was stirred anadditional three hours during which period the temperature was allowedto warm to room temperature. The microencapsulated product was isolatedby pouring the slurry through an ASTM -18 stainless steel sieve toremove any large agglomerates and then collecting the capsules byfiltration. The collected capsules were washed successively with four100 ml portions of distilled water each and stored as a water wet pulp.A sample of the pulp analyzed by drying in vacuo at 80° C was found toconsist of 37.5 percent solids.

C. To 125 ml of distilled water, 10.6 g of oxidized corn starch wasadded over a period of ten to fifteen minutes with stirring. Thismixture was heated to a temperature in the range of 70°-80° C andmaintained until all the starch dissolved. The starch solution wascooled to ambient temperature and there was added 100 g of thecapsule-containing water wet pulp from part B above and 43.0 ml ofdistilled water. The capsules and starch solution were mixed at roomtemperature using an Eppenbach Homo-Mixer set at an applied voltage of25 volts for five minutes and then at an applied voltage of 30 volts foran additional five minutes to complete the suspension of the capsules inthe starch solution.

D. The stock starch-microcapsule suspension prepared in part C above wascoated on paper sheets to a thickness of approximately 0.0015 inch andthe coated paper air dried. The paper thus coated with themicroencapsulated colorless precursor was assembled as the top sheet ina manifold system by positioning the coated side in contact with thecoated side of a commercially available receiving sheet coated with acolor developer of the electron accepting type. More specifically,papers coated with a phenolic resin and with an acidic clay wereemployed in this test. An image was then drawn with a stylus on the topsheet bearing the microencapsulated colorless precursor on its reverseside causing the affected microcapsules to rupture thus allowing thesolution of the colorless precursor held by said microcapsules to flowinto contact with the color developing substance on the receiving sheetwhereupon a deep blue-colored image promptly formed. The developed imageexhibited good lightfastness when exposed to daylight or to a daylightfluorescent lamp for extended periods.

When evaluated in a duplicating system prepared and tested as describedabove, the product of Example 3B,3,5,5-tris(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone, produced ablue-colored developed image; the product of Example 6,2,5-bis(1-ethyl-2-methyl-3-indolyl)-5-(1-n-butyl-2-methyl-3-indolyl)-2(5H)-furanone,produced a blue-colored developed image; the product of Example 20B,3,5-bis(1-n-butyl-2-methyl-3-indolyl)-5-(2-methyl-3-indolyl)-2(5H)-furanone,produced a blue-colored developed image; and the product of Example 28,5,5-bis(1-ethyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone,produced a purple-colored developed image.

EXAMPLE 42

The utility of the furanones of Formulas I and II whose preparations aredescribed in the foregoing examples as color forming components inthermal marking systems is illustrated by the incorporation and testingof the compound of Example 28,5,5-bis(1-ethyl-2-methyl-3-indolyl)-2,3-dichloro-2(5H)-furanone in athermal sensitive marking paper. The test paper was prepared by aprocedure similar to that described in U.S. Pat. No. 3,539,375.

A. A mixture of 20 g of5,5-bis(1-ethyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone, 8.6 gof a ten percent aqueous solution of polyvinyl alcohol (approximately 99percent hydrolyzed), 3.7 g of water and 31.6 g of 1/16 inch diameterzirconium grinding beads was charged into a container which was placedin a mechanical shaker. Shaking was effected for one hour. The zirconiumbeads were then removed by straining the mixture through a No. 40 sieve.

B. Similarly, a mixture of 9.8 g of 4,4'-isopropylidine diphenol(Bisphenol A), 42.0 g of a ten percent aqueous polyvinyl alcoholsolution (approximately 99 percent hydrolyzed), 18.2 g of water and221.2 g of 1/16 inch diameter zirconium grinding beads was charged intoa container which was placed in a mechanical shaker. After shaking waseffected for one hour, the zirconium beads were removed by strainingthrough a No. 40 sieve.

C. A coating composition was prepared by mixing 2.1 g of the slurry fromA and 47.9 g of the slurry from B. The mixture was then uniformly coatedon sheets of paper at thicknesses of approximately 0.003 inch and thecoated sheets air-dried. The coated paper was tested by tracing a designon the coated side of the paper on a smooth flat surface with a stylusheated to approximately 140° C. A deep brownblack image corresponding tothe traced design promptly developed.

When evaluated in thermal marking paper prepared and tested as describedabove, the product of Example 4B,3,5,5-tris(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone, produced a deepblue image; the product of Example 22B,3,5-bis-(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanone, produced ayellow-green image; the product of Example 31,5-(1-ethyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone, produced ayellow-brown image; and the product of Example 22A,3,5-bis(1-ethyl-2-methyl-3-indolyl)-2(3H)-furanone, produced agreen-blue image.

EXAMPLE 43

A. Proceeding in a manner similar to that described in Example 42 above,2.0 g of the compound of Example 31,5-(1-ethyl-2-methyl-3-indolyl)-3,4-dichloro-2(5H)-furanone was ground ina mixture of 8.6 g of a ten percent aqueous solution of polyvinylalcohol and 3.7 g of water.

B. A mixture of 47.9 g of ten percent aqueous polyvinyl alcohol, 22.1 gof water and 221.2 g of 1/16 inch diameter zirconium grinding beads wascharged to a container and placed in a mechanical shaker. Shaking waseffected for one hour and thhe zirconium beads were separated from thesolution by screening through a No. 40 sieve.

C. A coating composition consisting of 2.1 g of the slurry from part Aabove and 47.9 g of the slurry from part B above was prepared and coatedon paper sheets to a thickness of approximately 0.003 inch and thecoated sheets were air-dried. The coated paper was tested by tracing adesign on the coated side of the paper placed on a smooth flat surfacewith a stylus heated to approximately 200° C. A greenish-brown imagecorresponding to the traced design promptly developed.

What is claimed is:
 1. A 3,5-bis(1-R-2-R₁ -5/6-Y-3-indolyl)-5-(1-R₂-2-R₃ -5/6-Y₁ -3-indolyl)-2(5H)-furanone having the formula ##STR12##wherein: R and R₂ represent hydrogen, non-tertiary alkyl of one to eightcarbon atoms, alkenyl of two to four carbon atoms, benzyl or benzylsubstituted in the benzene ring by one or two of halo or alkyl of one tothree carbon atoms;R₁ and R₃ represent hydrogen, alkyl of one to threecarbon atoms or phenyl; and Y and Y₁ represent one or two of hydrogen,alkyl of one to three carbon atoms, alkoxy of one to three carbon atoms,halo or nitro. 2.3,5-Bis(1-n-propyl-2-methyl-3-indolyl)-5-(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 3.3,5,5-Tris(1-n-propyl-2-methyl-3-indolyl)-2(5H)-furanone according toclaim
 1. 4. 3,5,5-Tris(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim 1.5.3,5-Bis(1-ethyl-2-methyl-3-indolyl)-5-(1-n-butyl-2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 6.3,5-Bis(1-ethyl-2-methyl-3-indolyl)-5-(1-n-propyl-2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 7.3,5-Bis(1-ethyl-2-methyl-3-indolyl)-5-(1,2-dimethyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 8.3,5-Bis(1-ethyl-2-methyl-3-indolyl)-5-(2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 9. 3,5,5-Tris(2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 10.3,5-Bis(2-methyl-3-indolyl)-5-(1,2-dimethyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 11.3,5-Bis(2-methyl-3-indolyl)-5-(1-ethyl-2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 12.3,5-Bis(2-methyl-3-indolyl)-5-(2-phenyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 13.3,5-Bis(2-methyl-3-indolyl)-5-(1-n-octyl-2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 14.3,5-Bis(2-methyl-3-indolyl)-5-(1-allyl-2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 15.3,5-Bis(2-methyl-3-indolyl)-5-(1-benzyl-2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 16.3,5-Bis(2-methyl-3-indolyl)-5-(1-n-butyl-2-methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 17.3,5,5-Tris(1,2-dimethyl-3-indolyl)-2(5H)-furanone according to claim 1.18.3,5-Bis(1,2-dimethyl-3-indolyl)-5-(1-ethyl-2methyl-3-indolyl)-2(5H)-furanoneaccording to claim
 1. 19.3,5-Bis(1-n-butyl-2-methyl-3-indolyl)-5-(2-methyl-3-indolyl)-2(5H)-furanoneaccordng to claim
 1. 20.3,5,5-Tris(1-n-butyl-2-methyl-3-indolyl)-2(5H)-furanone according toclaim 1.